Catalyst Development

Esterquats are cationic surfactants, which are increasingly used because of their softening effect and excellent biodegradability compared to the conventional quats. This paper highlights the uses of palm-based esterquats as an active ingredient in the ...

CHAPTER 1 INTRODUCTION 1.1 SYNTHESIS OF NITROGEN CONTAINING HETEROCYCLES The chemistry of heterocyclic compounds is one of the interesting branches of organic chemistry for the diversity of its synthetic procedures, physiological and industrial significance. Nitrogen containing heterocyclic compounds, such as quinolines, indoles, pyrroles, pyridines, pyrazines and pyrrolidines are of high industrial interest for application as intermediates to produce pharmaceuticals, herbicides, fungicides and dyes. Currently most of these compounds are recovered by distillation of coal tar. Alternatively, they are also obtained by well-known liquid-phase syntheses such as Skraup's, Fischer, Madelung's, Chichibabin's reactions. However, they have many important drawbacks, such as, use of hazardous reaction conditions, expensive or toxic feeds and large waste production (Kartritzky et al 1997, Koleter et al 1973, Watanabe et al 1990). Recently, novel reactions and/or processes have been investigated, shifting the balance from an exclusive focus on yield to the one that places economic value on minimizing wasteful byproducts and operating in more safer conditions. Increasing attention is being focused on the vapor phase synthesis of nitrogen containing compounds with heterogeneous catalysts that exhibit significant advantages in comparison to homogeneous catalysts. The major advantages include continuous production, simplified product recovery, regeneration of catalyst and reduction in liquid waste streams (Hardt 1983). NH 2 NH 2

Graphitic carbon nitride was synthesized via thermolysis of urea and then ultrasonic exfoliated from colloidal solution to obtain phase pure ultrafine powder of g-C 3 N 4 . It was shown that ultrasonic-assisted exfoliation of the initial graphitic carbon nitride powder leads to an increase in its phase purity (PXRD), a change in the morphology (SEM), a decrease in the band gap from 2.93 eV to 2.85 eV (DRS) and an increase in the specific surface from 58.6 m 2 /g to 136.7 m 2 /g (BET). In addition, it was found that the exfoliated g-C 3 N 4 is an effective catalyst for the process of electrocatalytic reforming -the hydrogen evolution from the water-alcohol solution. Based on volamperometry, it was found that the hydrogen overpotential of graphitic carbon nitride is equal to 249 mV (at 10 mA/cm 2 ), and the Taffel slope is 112 mV/dec. The results of cyclic voltammetry of the electrode based on exfoliated g-C 3 N 4 indicate its high stability, which allows us to consider the exfoliated graphitic carbon nitride as a promising basis of materials for electrocatalytic reforming of alcohols.

2018 Summer.Includes bibliographical references.Lean burn two stroke engines are used extensively for stationary applications including power generation, cogeneration and compression. Natural gas is abundant, relatively inexpensive, and combustion produces less CO2, particulate matter, and SOx than gasoline and diesel. However, the Natural gas industry continues to be impacted by increasingly stricter emissions limits. One approach to comply with these emission limits is outfitting engines with an oxidation catalyst. Oxidation catalysts are proven to reduce hydrocarbon and carbon monoxide emissions, but surface poisoning due to lube oil carry over diminishes performance. Zinc, phosphorus, and sulfur found in oil additives poison the catalysts surface, and readily leach into an acidic environment. Two commercial catalyst modules were aged at a field site on a slipstream of a GMVH-12 engine until they no longer met the National Emissions Standards for Hazardous Air Pollutants (NESHAP)...

The thermochemical process converts almost any kind of biomass to a desired final product, i.e. gaseous or liquid transportation fuels and chemicals. The transportation fuels obtained in this way are renewable biofuels, which are alternatives to fossil fuels. During the last few years, thermochemical plants for the production of bioethanol have been launched and another is under construction. A total of about 290 million liters of ethanol are expected to be processed per year, mostly using municipal solid waste. Considerable efforts have been made in order to find a more selective catalyst for the conversion of biomass-derived syngas to ethanol. use of mesoporous catalyst have been found over a Cu/MCM-41 catalyst, shown in Paper V. Also in Paper V, the effect of metal promoters (Fe and K) has been studied; a noticeable increase of ethanol reaction rate was found over Cu-Fe-K/MCM-41 catalyst as compared to Cu/MCM-41.

Hydroxyapatite, a bioceramic material, possesses sufficient stability in aqueous and organic medium and it is mainly known for its role in tooth and bone structure. However, it is less-known that, in certain conditions, the HA can be used as a catalyst in its free, metal-doped and composite forms. HA as a catalyst is generally prepared by i mpregnation or co-precipitation methods, sometimes from natural P-containing wastes. HA can be doped with mono-or polymetallic ions or nanoparticles and can contain other admixtures or supports (i.e., carbon). Different Ca/P ratios (ideal 1.67; the ranges are 1.5e1.7 in synthetic and 1.5e1.8 in biologic forms) can be revealed for the HA. Nanosized HA forms are frequent in several applications. A variety of distinct processes can be HA-catalyzed, such as oxidation of alcohols, dehydrogenation, hydrogenation and hydrogenolysis, CC bond formation, among other important existing low-and large-scale organic processes. The HA can be also used for catalytic environmental remediation, CO 2 fixation, and N 2 O decomposition. In this review, we emphasize most recent advances (mainly last decade) on the catalytic HA applications, except for biomedical ones.

This paper presented the kinetic study of molybdenum borides via the Volmer-Heyrovsky-Tafel (V-H-T) mechanistic steps for hydrogen evolution reaction (HER). A theoretical approach was carried out to investigate the kinetic properties of several molybdenum boride materials for HER in 0.5 M H2SO4. Our findings offer definitive proof that the simulated results show that B, Mo, Mo2B, and α-MoB, proceed through V-H mechanistic steps (slower kinetics) while β-MoB and MoB2 exhibit V-H-T mechanistic steps with higher kinetics. The kinetic parameters were determined in terms of the standard rate constant parameters for the Volmer step (kV, k-V), Heyrovsky step (kH, k-H), and rate constant for the Tafel step (kT, k-T). The simulation was able to predict the overpotential at 10 mA/cm2, η10 recorded at approximately 780, 585, 480, 350, 310, and 300 mV for B, Mo, Mo2B, α-MoB, β-MoB, and MoB2 respectively. Based on these findings, the adopted mathematical model shows good coherency to the experimental findings. The simulation work provides a good numerical estimation of the characteristics of the electrocatalyst for HER. This paper successfully elucidated the reaction mechanisms (V-H-T steps) and understood the rate-limiting steps involved in the HER process on Mo-B materials.

Biomass gasification as a thermochemical treatment method is typically used for heat and power production. Instead of burning the producer gas, it can be converted to added-value products, i.e to fuels and chemicals. One such conversion is the catalytic Fischer-Tropsch synthesis (FTS) which converts synthesis gas to a chain of aliphatic hydrocarbons (FT diesel) as studied in this thesis. This requires, however, proper cleaning steps of producer gas, such as the removal of tar compounds and other impurities. These cleaning steps are not considered in this thesis. The first goal of the thesis was to determine the tar content in the producer gas from a small scale biomass gasifier. This subject is discussed in Paper I. The second and main goal of the thesis was the preparation and characterization of cobalt (or iron) catalysts for catalytic conversion of a gas mixture close to the synthesis as discussed in Papers II-V. The overall aim of the second part was to study the effects of promoters on the reducibility of cobalt and the effects of different calcination conditions on the degree of reduction and size of the metallic cobalt particles. In this later part different catalytic supports were used. According to the results of the thesis, naphthalene and toluene were the main tar compounds in the producer gas representing almost 80 % of the GC detected tar compounds. Only traces of polycyclic aromatic compounds were detected and no phenolic compounds were found in the gas. Further, a number of supported heterogeneous catalysts for FTS using cobalt (Co) or in some cases iron (Fe) as the active metal were prepared and characterized. These catalysts were supported on alumina (Al 2 O 3), titanium dioxide (TiO 2) or silicon carbide (SiC). Catalysts were promoted with Ru, Re or Rh in the concentrations of 0, 0.2, 0.5, and 1.0 mass-%. Several characterization methods (such as H 2-TPR, catalytic activity measurements, N 2 physisorption, CO chemisorption, X-ray photoelectron spectroscopy (XPS), and X-ray diffraction (XRD)) were used to find answers to the behaviour of these catalysts under selected conditions and in the model reaction of FTS. Based on the results, there are significant differences in the characteristics of the catalysts, the differences are dependent of the supports used, promoters added and calcination conditions used. The properties of the support, especially the pore size distribution will effect the distribution of products formed in the Fischer-Tropsch synthesis. Addition of promoters and variatons in calcination conditions will effect the dispersion and the particle size of the active metal.

Exhaust pollutants from the automobile engines have negative impact on air quality as well as on human health. Exhaust emission control by catalytic converter, is best way to reduce emission for automotive vehicles. Catalytic converter generally used in modern automobile vehicles is based on noble metal (platinum, rhodium and palladium). Catalytic converter based on noble metal has certain demerits. Research in area of non-noble meal based catalytic converter to be developed for reducing pollution generated by automobile diesel engine. Current study focuses on new developed Ferric Oxide based catalytic converter because existing available catalytic converters suffer from various problems like; poisoning, fracture, melting and higher cost.

Using density functional theory, this study investigates the changes that occur to the electronic and geometric properties of alkali metals doped with Pt12 clusters. The research shows that doping causes enormous changes in the geometric structure of the clusters, which makes them stable. This is particularly noticeable for K@Pt12 clusters. This research investigates frontier molecular orbitals and finds that Li@Pt12 and Na@Pt12 clusters have small Eg of 0.13 eV and 0.19 eV, respectively, which could make them better for electronic and photovoltaic uses.
Analysis of spin charge density indicates that in Li@Pt12 and Na@Pt12 clusters, the Pt12 cage contributes the most spin to the electronic structures, with little to no spin contribution from Li and Na atoms, while in K@Pt12, both the K+ ion and the Pt12 cage build up the electronic structure. Charge density analysis shows alkali metals
transfer electrons to the Pt12 cage, making ionic bonds in Li@Pt12 and metallic bonds in Na@Pt12, and K@Pt12 clusters, respectively. However, density of states (DOS) shows how new electronic states are created upon doping, altering the cluster’s electronic properties. Furthermore, the calculation of global reactivity descriptors indicates that doping alters the chemical reactivity and kinetic stability. Clusters of K@Pt12 show enhanced hardness and stability. The results of this research provide novel insight into Pt12 clusters doped with Li, Na, and K. Furthermore, it expands the abilities of computational chemists to design materials that propel technological advancement.

A carbonization-sulfonation method was utilized in synthesizing sulfonated mesoporous catalysts from palm tree biomass. Brunauer-Emmet-Teller (BET), powder X-ray diffraction (XRD), energy dispersive X-ray (EDX), and field emission scanning emission microscopy (FE-SEM) analyses were used to evaluate the structural and textural properties of the catalysts. Further, Fourier transform infrared (FT-IR) spectroscopy and titrimetric analyses measured the strong acid value and acidity distribution of the materials. These analyses indicated that the catalysts had large mesopore volume, large surface area, uniform pore size, and high acid density. The catalytic activity exhibited by esterifying used frying oil (UFO) containing high (48%) free fatty acid (FFA) content further indicated these properties. All catalysts exhibited high activity, with sPTS/400 converting more than 98% FFA into fatty acid methyl esters (FAMEs). The catalyst exhibited the highest acid density, 1.2974 mmol/g, determined by NaOH titration. This is outstanding considering the lower reaction parameters of 5 h, 5:1 methanol-to-oil ratio, and a moderate temperature range between 100 and 200 °C. The study further illustrates the prospect of converting wastes into highly efficient, benign, and recyclable solid acid catalysts.

Double promoted γ-alumina heterogeneous base catalyst (CaO/KI/γ-alumina) was firstly developed for the production of biodiesel from palm oil in refluxed methanol. This study have been conducted in order to improve the activity of single promoted catalyst (CaO/γ-alumina) and to enhance the efficiency of biodiesel production that have been done in the previous work. The CaO/KI/γ-alumina catalyst was prepared by precipitation and impregnation methods. Engineering catalyst done with some parameters that effect on the activity of a catalyst among other: % CaO loading (wt. % against alumina), temperature and time of calcinations. The catalyst was characterized by mean of XRD, and BET methods. The activity of catalyst has been tested by introduced to the transesterification reaction of palm oil. The reaction was carried out in the batch type of reactor (three-neck glass flask with 500 ml capacity) equipped with reflux condenser, thermometer and magnetic stirrer. The result showed that the optimum condition of preparation catalyst (% of CaO loading, temperature and time of calcinations) were 30%, 650°C and 4.5 h, respectively. Under the optimum condition of catalyst, reaction temperature 65°C, reaction time 5 h and oil to methanol molar ratio of 1:42 the biodiesel yield was almost 95%. Therefore, it can be proved that the activity of double promoted catalyst (CaO/KI/γ-alumina) much higher than that the single promoted (CaO/γ-alumina) catalyst.

Fischer-Tropsch Synthesis (FTS) is a non-crude oil-based technique for conversion of syngas to a wide range of hydrocarbons including light olefins, and liquid transportation fuels. Syngas, which is a combination of H2 and CO gases can be produced through natural gas reforming, biomass or coal gasification processes. FTS is a catalytic polymerization reaction, therefore rational design of the catalyst including active sites, support and promoters plays a significant role in improving the selectivity of the process to desired range of products. This mini review presents a summary of the different catalyst designs in FTS to synthesize light olefins or heavier hydrocarbons. Iron and cobalt are the industrially used active metals for FTS, due to the lower price and higher hydrogenation activity, respectively. Supports are a key factor in designing efficient FTS catalysts, which provide mechanical, thermal strength for the active sites and a high surface area for dispersion of the active metal particles. Herein we discuss two categories of the widely used support material for FTS: metal oxide supports and carbon materials. Another significant element in formulating a high-performance catalyst for FTS process is the promoters, which can be divided into electronical and structural promoters. This work highlights the roles of active metal, support and promoters in understanding the structure-activity correlations to design high-performance FTS catalysts for production clean and sustainable fuels.

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Catalysis of the hydrogen evolution reaction (HER) is important in the development of an energy economy based on clean hydrogen gas. In this work, we report a new catalyst material for the generation of hydrogen via hydronium reduction. The new material, which consists of MoO 2 , sulfur, and graphene, was prepared by co-reduction of molybdenum salt and graphite oxide in air in the presence of focused solar radiation. The potential utility of this material for HER catalysis was evaluated by cyclic and linear-sweep voltammograms and compared against a Pt/C commercial catalyst. The MoO 2 /graphene hybrid nanocomposite exhibits a Tafel slope of 47 mV/dec and hydrogen evolution at a potential onlỹ 120 mV more negative than the standard Pt/Carbon catalyst at 10 mA/cm 2 current density. The hydrogen gas generated by the catalytic material was measured using gas chromatography. The simple synthesis and low overpotential suggests that this hybrid composite has potential as an HER catalyst.

Fischer-Tropsch synthesis (FTS) has been studied at 5 • 103 Pa, at 508 K, an H 2/C0 = 2/1 molar ratio on Ru/T-A120 3 catalysts (1% Ru wt./wt.), using Ru(AcAc) 3 (AcAc standing for acetylacetonate), RuC13 and K(AcAc) as precursors; K/Ru and C1/Ru molar ratios ranged from 0.14 to 2.18 and from 1.31 to 3.71, respectively. As Ru catalysts for FTS undergo easy alteration resulting from coke deposition, the results from kinetic runs were collected using both fresh catalysts (at 5-10 min time-on-stream) and also when steady state conditions were reached (about 150 min time-on-stream). The influence of K/Ru and CI/Ru ratios on CO conversion and on the selectivity of the formation of different products in the reaction has been examined. Changes in activity, during the regeneration procedures of the catalysts, differ significantly when the precursor is Ru(AcAc) 3 (increase in activity after regeneration cycle) or RuCI 3 (significant deactivation with a decrease in Ru surface concentration, as determined by XPS).

Fischer-Tropsch synthesis (FTS) has been studied at 5 • 103 Pa, at 508 K, an H 2/C0 = 2/1 molar ratio on Ru/T-A120 3 catalysts (1% Ru wt./wt.), using Ru(AcAc) 3 (AcAc standing for acetylacetonate), RuC13 and K(AcAc) as precursors; K/Ru and C1/Ru molar ratios ranged from 0.14 to 2.18 and from 1.31 to 3.71, respectively. As Ru catalysts for FTS undergo easy alteration resulting from coke deposition, the results from kinetic runs were collected using both fresh catalysts (at 5-10 min time-on-stream) and also when steady state conditions were reached (about 150 min time-on-stream). The influence of K/Ru and CI/Ru ratios on CO conversion and on the selectivity of the formation of different products in the reaction has been examined. Changes in activity, during the regeneration procedures of the catalysts, differ significantly when the precursor is Ru(AcAc) 3 (increase in activity after regeneration cycle) or RuCI 3 (significant deactivation with a decrease in Ru surface concentration, as determined by XPS).

In this work, we used a dissociative mechanism to perform calculations based on Density Functional Theory, DFT, and electronic structure in order to study the oxygen reduction reaction on graphene doped with iron. The model takes into account some of the operating conditions of a proton exchange membrane fuel cell such as the equilibrium of hydrogen oxidation reaction, electrode potential of 1.23 V and 0 V, solvation effects, and corrections to the energy at the zero point (ZPE) and the entropic one. However, in this approach, we neglect the effects on the free energy of the interaction of the adsorbed species with the electric field due to the double electrochemical layer, the pH of the acid medium, and the oxygen coverage. The free energy diagrams for different intermediate steps of the oxygen reduction reaction, ORR, the oxygen adsorption energy on sites close to those occupied by the Fe-atoms, as well as the activity calculations indicated that Fe-Graphene (Fe-G) system, may possess catalytic properties close to either Pt, as catalyst, as its alloys since they can favor the ORR in a fuel cell proton exchange membrane. The results have been compared with other theoretical studies which use graphene as a central element as will be established in the present manuscript.

Density functional theory (DFT) in conjunction with virtual crystal approximation is used to study the oxygen reduction reaction (ORR) as a function of the cooper concentration in PdeCu disordered binary alloy metal surfaces and as a function of applied bias. The study is realized calculating the free energy diagrams of all intermediates. Reactivity is evaluated on the basis of an oxygen reduction reaction (ORR) dissociative mechanism of four steps, it involves the splitting of the OeO bond in O 2 after its adsorption, followed by hydrogenation of atomic O to OH. Then, the OH species undergoes another hydrogenation to yield H 2 O. For each concentration of Cu, results for low oxygen coverage are presented at zero cell potential (U ¼ 0), at the equilibrium potential (U ¼ 1.23 V), and at the highest potential (U ¼ 0.80 V) where all reaction are exothermic. The results indicate that at the ORR equilibrium potential of 1.23 V, the reactivity of all surfaces is shown to be limited by the rate of OH removal from the surface, while that at a cell potential of 0.80 V, the ORR reactivity of different surfaces is dictated by the hydrogenation of O * and strength of oxygen adsorption. The results are compared with other non-Pt alloys.

A new class of green solvents, known as ionic liquids (ILs), has recently been the subject of intensive research on the extractive desulfurization of liquid fuels because of the limitation of traditional hydrodesulfurization method. In present work, eleven Lewis acid ionic liquids were synthesized and employed as promising extractants for deep desulfurization of the liquid fuel containing dibenzothiophene (DBT) to test the desulfurization efficiency. [Bmim]Cl/FeCl3was the most promising ionic liquid and performed the best among studied ionic liquids under the same operating conditions. It can remove dibenzothiophene from the model liquid fuel in the single-stage extraction process with the maximum desulfurization efficiency of 75.6%. It was also found that [Bmim]Cl/FeCl3may be reused without regeneration with considerable extraction efficiency of 47.3%. Huge saving on energy can be achieved if we make use of this ionic liquids behavior in process design, instead of regenerating ioni...

Highlights  Few-layered MoS2 are deposited onto 3D interconnected porous carbon nanosheets to increase the exposure of active edges.  The few-layered MoS2 are vertically aligned on the 3D interconnected porous carbon nanosheets through a simple solvothermal reduction method.  The obtained nanocomposite shows an excellent catalytic activity in HER.

Extraction of neutral nitrogen-containing compounds (N-compounds) has been investigated with chloride based ionic liquids (ILs) with varying cation classes (imidazolium, pyridinium). ILs were first discriminated by their mutual solubility of ILs and model fuel. Low solubility of 1-butyl-3-methylimidazolinium chloride (BMImCl) and 1-octylpyridinium chloride (OcPyCl) in the model fuel was observed. The ILs were then evaluated using a synthetic solution with dibenzothiophene and carbazole as model compounds, and a high selectivity for N-compounds was found. BMImCl and OcPyCl were then evaluated using straight-run diesel feed, containing 13 400 ppm S and 105 ppm N. An extraction of up to 50% of the N-compounds was obtained in one step whereas the sulfur concentration reduction was only 5%. Both ILs can be regenerated using small amount of water. Extracted compounds could be then extracted using toluene. The major constituents were identified by GC-MS. Analysis of the extracted compounds emphasized the selectivity of the extraction process. Furthermore, refractory sulfur-containing compounds (S-compounds) and polyaromatics were also identified in the extract.

Aluminum chloride-urea ionic liquid was investigated for its active species concentration with the aide of electronic spectroscopy by Lewis acid-base titration with chloride ions. A coordination bonds between aluminum cationic species of the ionic liquid and the aromatic ring of toluene or benzene was assumed to be responsible for new formed bands in visible and ultraviolet regions. Upon Lewis acid-base titration these bands disappeared and the concentration of the acidic species were elucidated to be around 75 mole% of the initial aluminum chloride used to prepare a 1.5 mole aluminum chloride to 1 mole urea ionic liquid. The product of this reaction assumed to be between 1 acidic species to 1 chloride ion according to the mole fraction elucidated graph.

A CuO-ZnO-Al 2 O 3 catalyst was synthesized by an ultrasound assisted co-precipitation method and compared with the one synthesized by a conventional co-precipitation method. The characterization results of XRD, BET, FESEM and FTIR indicated that the physicochemical properties of the catalysts are strongly influenced by the formulated precursor and the synthesis method. The morphology of the catalyst precipitated under ultrasound irradiation was well-defined and agglomoration-free with average size particle of 32.3 nm. The dispersion of CuO and the surface area of the catalyst exhibited an improvement in acetate based catalyst. The high degree of synergism effect between CuO and other components in CuO-ZnO-Al 2 O 3 catalyst was expected in the acetate-based catalyst synthesized with ultrasound assisted co-precipitation method due to low crystallinity and small size of copper species. The catalytic performance for the synthesis of methanol was examined at 200-300°C and 10-40 bar in a stainless steel reactor. The CuO-ZnO-Al 2 O 3 catalyst synthesized from acetate precursor precipitated under ultrasound irradiation exhibited a supreme catalytic activity at 275°C, 40 bar, 18,000 cm 3 /g h and H 2 /CO = 2 in terms of CO conversion and methanol yield.

A CuO-ZnO-Al 2 O 3 catalyst was synthesized by an ultrasound assisted co-precipitation method and compared with the one synthesized by a conventional co-precipitation method. The characterization results of XRD, BET, FESEM and FTIR indicated that the physicochemical properties of the catalysts are strongly influenced by the formulated precursor and the synthesis method. The morphology of the catalyst precipitated under ultrasound irradiation was well-defined and agglomoration-free with average size particle of 32.3 nm. The dispersion of CuO and the surface area of the catalyst exhibited an improvement in acetate based catalyst. The high degree of synergism effect between CuO and other components in CuO-ZnO-Al 2 O 3 catalyst was expected in the acetate-based catalyst synthesized with ultrasound assisted co-precipitation method due to low crystallinity and small size of copper species. The catalytic performance for the synthesis of methanol was examined at 200-300°C and 10-40 bar in a stainless steel reactor. The CuO-ZnO-Al 2 O 3 catalyst synthesized from acetate precursor precipitated under ultrasound irradiation exhibited a supreme catalytic activity at 275°C, 40 bar, 18,000 cm 3 /g h and H 2 /CO = 2 in terms of CO conversion and methanol yield.

Fischer-Tropsch (FT) synthesis activity and the stability of a Co/SiO 2 catalyst modified with Mn-and Zr were examined under various practical conditions. Dependence of FT synthesis on reaction pressure and benchscale FT synthesis were investigated. Evaluating catalyst lifetime during continuous FT reactions was conducted. The Co + Mn + Zr/SiO 2 catalyst exhibited relatively greater activity and stable reactivity for 168 h. Sulfur resistance of catalysts were investigated and results showed that the presence of 4 ppm H 2 S drastically affected catalytic activity. The Co + Mn + Zr/SiO 2 catalyst exhibited greater activity even with H 2 presence and the sulfur poisoning rate was almost similar on both Co + Mn + Zr/SiO 2 and Co/SiO 2 catalysts.

The partial oxidation (POx) reforming of Ultra Low Sulphur-Diesel (ULSD), rapeseed methyl ester (RME)-biodiesel and Fischer-Tropsch synthetic diesel fuels (SD) were studied by using a fixed-bed reactor. The ease of reforming the three fuels was first examined at different O/C feed ratios at constant gas hourly space velocity (GHSV) of 35 k h À1 over a prototype monolith catalyst (1%Rh/CeO 2-ZrO 2). The hydrocarbon species (C 1-C 6) produced in the reformer were analyzed using direct gas injection gas chromatography mass spectrometry (GC-MS). Under the same O/C ratios for 35 k h À1 the fuels conversion and process efficiency was dependent on the fuel type, and followed the general trend: SD > biodiesel > ULSD. The GC-MS analysis shows that both, biodiesel and ULSD diesel produced significantly higher amounts of alkenes compared to SD fuel. Fuel with relatively high aromatics content such diesel can be efficiently reformed to syngas over the catalyst used in this study but the reformer operating range (e.g. O/C ratio and space velocity) is limited compared to paraffinic fuels such as FT-SD. At increased GHSV of 45 k h À1 and O/C ¼ 1.75, the diesel fuel conversion efficiency to syngas (H 2 and CO) was improved significantly and the formation of intermediate species such as methane, ethylene, and propylene was reduced considerably as a result of the increased peak reaction temperatures. The reduced HC species and increased H 2 concentration in the reactor product gas from the reforming of FT-SD fuel can provide significant advantages to the IC engine applications.

The Fischer-Tropsch synthesis (FTS) for the conversion of carbon monoxide and hydrogen to higher hydrocarbons was investigated over a supported Cu/Co catalyst promoted by dielectric-barrier discharges (DBDs) at relatively low temperatures and ambient pressure. The effect of plasma power, operation pressure, and H 2 /CO molar ratio on the activity and selectivity of the catalyst in a DBD reactor were studied. The fresh and used catalyst samples were characterized by scanning electron microscopy, transmission electron microscopy, energy dispersive X-ray, and X-ray diffraction. We also used DBDs in catalyst preparation as a technique to enhance metal distribution on the catalyst support. The present study reveals that plasma can promote the FTS over a Cu/Co-based catalyst at low temperatures and ambient pressure. The formation of methane was strongly suppressed in plasma. In contrast to conventional FTS, CO conversion was higher at low operating pressure than that at higher pressure in the DBD-promoted FTS, which indicates the presence of a new reaction path for FTS.

Exploring efficient noble-metal-free water splitting electrocatalysts from earth-abundant elements is of great importance to realize wide applications in the generation of hydrogen fuel for clean energy. Here we reported a facile route to synthesize ε-Fe 3 N single-phase nanoparticles by thermal ammonolysis of Fe precursors. The roles of nitrogen atoms in tailoring the hydrogen evolution reaction (HER) activities of ε-Fe 3 N have been systematically investigated. HER activity is enhanced by reducing the effective coordination number of nitrogen atoms from 2.61 to 1.67, where the standard coordination number in ε-Fe 3 N is 2. Density functional theory (DFT) calculations reveal that the reduction of nitrogen content lowers the energy of the Tafel process on the (̅ 100)-FeN exposed and (11 ̅ 0) N-exposed surfaces. Both surfaces are thermodynamically favored for the HER. Furthermore, the active sites of the Tafel process changes from the kinetically less favored hollow sites of Fe atoms to the kinetic more favored top site of N atoms and the bridge site of Fe atoms on both (̅ 100)-FeN and (11 ̅ 0) N-exposed surfaces. Our findings propose a novel strategy to enhance This article is protected by copyright. All rights reserved. 3 HER activity by utilizing nitrogen deficiency, which is of great importance for the development of highly active transition metal based electrocatalysts.

This review aims to provide an overview of the main catalytic studies of H 2 production by ethanol steam reforming (ESR). The reaction is endothermic and produces H 2 , CO 2 , CH 4 , CO and coke. The conversion and H 2 selectivity of these products depended greatly of the physicochemical properties of the catalysts, active metal, promoters, temperature, longterm reaction, water/ethanol ratio, space velocity, contact time, and presence of O 2. Initial total conversion has been reported in all catalysts evaluated between 300 and 850 C. The noble catalysts with high selectivity to H 2 (more than 80%) were: Rh, Ru, Pd and Ir and non-noble metal catalysts were: Ni, Co and Cu. The support materials include CeO 2 , ZnO, MgO, Al 2 O 3 , zeolites-Y, TiO 2 , SiO 2 , La 2 O 2 CO 3 , CeO 2 eZrO 2 and hydrotalcites. The impregnation method produced the best noble metal catalysts in terms of selectivity and conversion. The decrease of coke was related with the presence of basic sites on the support.

The advantages of homogeneous transition catalysts are to some extend damped by the necessity to separate, and if possible recycle, the catalyst from the solution. Immobilization of catalysts on a solid support is a frequently used strategy, but the general drawback is a lower catalyst activity and selectivity. We now report a new strategy to monitor catalyst immobilization by imaging with two-photon fluorescence microscopy at sub-micrometer level. To this end a diphosphine ligand with intrinsic fluorescent properties, which gives rise to active and selective rhodium hydroformylation catalysts was immobilized on a glass surface using traditional methods. The imaging of the immobilized ligand uncovered clustering of the ligands and therefore of the catalyst particles, explaining part of the deterioration of the catalyst performance compared to the homogeneous phase system. Based on these results a simple new immobilization process was developed that did not give rise to clustering and the supported rhodium catalysts gave activities and selectivities that are close to the homogeneous catalyst, with the advantage that separation and recycling can be done by simple filtration processes.. Catalyst recovery is an important topic in the area of homogeneous catalysis since the product-catalyst separation is one of the main obstacles towards application of these classes of catalysts. So far, several strategies for catalyst recycling have been explored, 1 but a general strategy remains elusive. A widely studied approach to facilitate catalyst-product separation is the attachment of homogeneous catalysts to polymeric organic, inorganic, hybrid, or dendrimeric supports. 2-5 Inorganic materials have shown to be particularly suited as solid support for homogeneous catalysts because of their physical strength and chemical inertness and many of such immobilized catalytic systems have been reported. A common drawback, however, remains the generally lower activity and selectivity compared to the homogeneous counterpart. It is known that the properties of the solid support affects the catalytic reaction to a certain extend. Surprisingly, an in-depth investigation of the effect of the immobilization process on the

The advantages of homogeneous transition catalysts are to some extend damped by the necessity to separate, and if possible recycle, the catalyst from the solution. Immobilization of catalysts on a solid support is a frequently used strategy, but the general drawback is a lower catalyst activity and selectivity. We now report a new strategy to monitor catalyst immobilization by imaging with two-photon fluorescence microscopy at sub-micrometer level. To this end a diphosphine ligand with intrinsic fluorescent properties, which gives rise to active and selective rhodium hydroformylation catalysts was immobilized on a glass surface using traditional methods. The imaging of the immobilized ligand uncovered clustering of the ligands and therefore of the catalyst particles, explaining part of the deterioration of the catalyst performance compared to the homogeneous phase system. Based on these results a simple new immobilization process was developed that did not give rise to clustering and the supported rhodium catalysts gave activities and selectivities that are close to the homogeneous catalyst, with the advantage that separation and recycling can be done by simple filtration processes.. Catalyst recovery is an important topic in the area of homogeneous catalysis since the product-catalyst separation is one of the main obstacles towards application of these classes of catalysts. So far, several strategies for catalyst recycling have been explored, 1 but a general strategy remains elusive. A widely studied approach to facilitate catalyst-product separation is the attachment of homogeneous catalysts to polymeric organic, inorganic, hybrid, or dendrimeric supports. 2-5 Inorganic materials have shown to be particularly suited as solid support for homogeneous catalysts because of their physical strength and chemical inertness and many of such immobilized catalytic systems have been reported. A common drawback, however, remains the generally lower activity and selectivity compared to the homogeneous counterpart. It is known that the properties of the solid support affects the catalytic reaction to a certain extend. Surprisingly, an in-depth investigation of the effect of the immobilization process on the

Improving catalytic performance of syngas conversion to form C 2 oxygenates on the Cu-based catalyst is still a challenge. Here, 2D h-BN material covered Cu confined catalysts (xh-BN/Cu) with different spatial dimensions are rationally designed to unravel the function of spatial dimension in tuning the activity and selectivity of C 2 oxygenates. The results show that the spatial dimension caused by h-BN coating in the h-BN/Cu catalyst can alter the dominant existence form of CH x (x=1-3) monomer and the corresponding activity and selectivity, in which the confinement effect arisen from h-BN coating with different spatial dimensions is confirmed to be the determined factor instead of the electronic effect. The screened 4.0h-BN/Cu catalyst has outstanding catalytic performance toward the production of dominant CH x (x=1-3) monomer and C 2 oxygenates. The finding provides the new design principle to rationally construct 2D material covered metal confined catalysts by adjusting the confined spatial dimension to improve catalytic performance.

We have investigated three-dimensional (3D) MoS2 nanoarchitectures doped with different amount of Ni to boost the hydrogen evolution reaction (HER) in alkaline environment, where this reaction is normally hindered. As a comparison, the activity in acidic media was also investigated to determine and compare the role of the Ni sites in both media. The doping of MoS2, especially at high loadings, can modify its structural and/or electronic properties, which can also affect the HER activity. The structural and electronic properties of the Ni doped 3D-MoS2 nanoarchitecture were studied by X-ray diffraction (XRD), Raman spectroscopy, scanning and transmission electronic microscopy (SEM; TEM), and X-ray photoemission Spectroscopy (XPS). XPS also allowed us to determine the Ni-based species formed as a function of the dopant loading. The HER activity of the materials was investigated by linear sweep voltammetry (LSV) in 0.5 M H2SO4 and 1.0 M KOH. By combining the physicochemical and electro...

From the past decades, microbial fuel cells (MFCs) have evolved as a green alternative to produce electrical energy from organic matter degradation. Cathode modification significantly enhances the overall MFC performance. In this work, we report on ZIF-8 and carbon nanotubes (CNTs) derived catalyst materials as cathode for MFC. The catalysts were prepared via high-temperature pyrolysis at 900 • C and were physically characterized by various analytical techniques. All the catalyst materials carry tubular arrangements of CNTs covering the ZIF-8 crystals and exhibit highly micro-mesoporous texture. The electrocatalytic activity for oxygen reduction reaction (ORR) was studied in 0.1 M phosphate buffer at a catalyst loading of 0.2 mg cm − 2. The FeCo-N-C@900 catalyst showed the highest ORR activity with half-wave potential of 0.71 V vs RHE and limiting current density of − 5.62 mA cm − 2 at 1900 rpm. When tested in MFC, FeCo-N-C@900 coated cathode delivered the maximum power density of 1557 mW m − 2 (comparable to Pt/C catalyst reaching P max of 1681 mW m − 2) with chemical oxygen demand (COD) removal efficiency of 87.3%. The Next generation DNA sequencing analysis revealed the accumulation of various exoelectrogenic bacterial strains i.e., Bacillus, Desulfovibrio, Comamonadaceae sp. etc. commonly found in anaerobic biomass and showing the successful enrichment of the biofilm responsible for oxidizing organic matter at the anode. The present study illustrates the potential of transitional metal-doped ZIF-8 and CNTs composite electrocatalysts for enhancing the power output of MFC with generating promising power and current densities.

Ionic Liquids (ILs), a new class of green solvents, have recently been undergoing intensive research on the removal of thiophenic sulfur species (e.g., dibenzothiophene) from liquid fuels because of the limitations of the tradition hydrodesulfurization process in removing these species. In this work, deep extractive desulfurization of liquid fuels by different ionic liquids are studied and employed as promising extractants for the model liquid fuel containing dibenzothiophene (DBT). 1-butyl-3-methylimidazolium chloride [Bmim]Cl was the most promising and novel ionic liquid and performed the best among the studied ionic liquids under the same operating conditions. It can remove dibenzothiophene from the liquid fuel in the single stage extraction process with the maximum desulfurization efficiency 77.15% under mild reaction conditions. It was also found that [Bmim] Cl can be reused without regeneration with considerable extraction efficiency.

The effect of K promotion on the CO hydrogenation activity and C 2-C 4 hydrocarbons selectivity of the 15 wt % Ni-10 wt % Mo/Al 2 O 3 catalyst was investigated in the 498-548 K range using unpromoted and 1-3 wt % K-promoted samples. CO 2 methanation tests at 523 K were used as a probe to confirm activity trends. Intrinsic kinetic data were obtained in the initial rate region on both unpromoted and 1 wt % K-promoted Ni-Mo catalysts. K promotion of the bimetallic Ni-Mo catalyst decreases both the activity and the specific activity of the Ni sites while increasing the C 2-C 3 olefin-to-paraffin ratio. The surface carbide mechanism with dissociative adsorption of hydrogen as the rate-limiting step gives the most plausible kinetic model among the models tested for both Ni-Mo and Ni-Mo-K catalysts.

Promotion par les métaux nobles de catalyseurs Fischer-Tropsch à base de cobalt : une revue-La synthèse Fischer-Tropsch est une part essentielle du procédé XTL (X-To-Liquids, avec X = Gaz, Biomasse ou Charbon) qui convertit du gaz de synthèse en hydrocarbures pour carburants propres. Les catalyseurs à base de cobalt supportés sur des oxydes inorganiques constituent le meilleur compromis pour la production de paraffines à longues chaînes carbonées et de cires. L'efficacité du procédé Fischer-Tropsch dépend très fortement de la performance du catalyseur à base de cobalt. La promotion de ce catalyseur par des métaux précieux peut très fortement améliorer ses performances. Cet article fait la revue des différents effets des métaux nobles sur la structure et la performance de catalyseurs à base de cobalt. Les impacts sur le coût et l'activité des catalyseurs apparaissent comme des éléments incontournables dans le design de catalyseurs performants pour la synthèse Fischer-Tropsch.

Telah dilakukan sintesis katalis Pd/Ce/Zeolit, sintesis dilakukan dengan cara impregnasi larutan garam palladium dan serium pada zeolit , kalsinasi dilakukan pada suhu 600 ºC dengan dialiri N2 selama 4 jam kemudian O2 selama 1 jam selanjutnya direduksi dengan H2 pada 900 ºC selama 5 jam. Karakterisasi katalis dilakukan dengan menggunakan difraktometer sinar-X dan uji katalitik dilakukan terhadap umpan gas CO, banyaknya CO yang terkonversi ditentukan dengan kromatografi gas. Disimpulkan bahwa spesies logam yang terbentuk adalah Pd(0), PdO, PdO2, Ce2O3,dan Ce6O11. Katalis Pd/Ce/zeolit pada konsentrasi Ce 3 % adalah yang terbaik mempunyai ukuran partikel PdO/ Ce2O3 279,09/263,69 dengan kemampuan konversi terhadap gas CO 78,789 % pada suhu 700 ºC.

In heterogeneous catalysis, the interface between active metal and support plays a key role in catalyzing various reactions. Specially, the synergistic effect between active metals and oxygen vacancies on support can greatly promote catalytic efficiency. However, the construction of high-density metal-vacancy synergistic sites on catalyst surface is very challenging. In this work, isolated Pt atoms were first deposited onto a very thin-layer of MoO3 surface stabilized on γ-Mo2N. Subsequently, the Pt-MoOx/γ-Mo2N catalyst, containing abundant Pt cluster-oxygen vacancy (Ptn-Ov) sites, was in situ constructed. This catalyst exhibited an unmatched activity and excellent stability in the reverse water-gas shift (RWGS) reaction at low temperature (300 ºC). Systematic in situ characterizations illustrated that the MoO3 structure on the γ-Mo2N surface could easily deoxidize into MoOx (2

Artykuł wyjaśnia, czym są i jaką rolę odgrywają katalizatory. Obrazowo działanie katalizatora przyrównano do estakady na rondzie, która przyspiesza ruch i kieruje go na właściwe tory. Katalizator także przyspiesza reakcję chemiczną i kieruje ją na właściwe tory - nie ulegając przy tym zużyciu.

Deep desulfurization of fuels by using ionic liquids (ILs) has gained notable attention and has been a subject of concern. This study aims at the extraction tendencies of two alkylated derivatives of an aromatic sulfur compound, 4-Methyldibenzothiophene (MDBT) and 4,6-Dimethyldibenzothiophene (DMDBT) from oil using four ILs namely, Ethylmethylimidazolium tetrafluoroborate [EMIM][TFB], Butylmethylimidazolium tetrafluoroborate [BMIM][TFB], Ethylmethylimidazolium thiocyanate [EMIM][SCN], Butylmethylimidazolium thiocyanate [BMIM][SCN] via molecular dynamics simulation. A interfacial phenomena of extraction pathway of MDBT and DMDBT in biphasic system of dodecane and ILs was studied at molecular level. The transfer of sulfur compounds during the extraction processes, were observed to be controlled by type of IL as well as sulfur compound and interfacial resistance. This study will also help in selecting an appropriate IL as an extractant and improving the process conditions.

A series of copper ion substituted MAl2O4 (M= Mg, Mn, Fe and Zn) spinels is prepared by a single step solution combustion synthesis (SCS) and tested for methanol steam reforming (MSR). The copper ion substituted Cu0.1Fe0.9Al2O4 appears to be the most active, showing ~98% methanol conversion at 300 °C with ~5% CO selectivity at GHSV= 30000 h-1 and H2O:CH3OH= 1.1. The analogous impregnated catalyst, CuO (10 at.%)/FeAl2O4, is found to be much less active. These materials are characterized by XRD, H2-TPR, BET, HRTEM, XPS and XANES analyses. Spinel phase formation is highly facilitated upon Cu-ion substitution, and Cu loading beyond 10 at.% leads to the formation of CuO as an additional phase. The ionic substitution of copper in FeAl2O4 leads to the highly crystalline SCS catalyst containing Cu 2+ ion sites that are shown to be more active than the dispersed CuO nano-crystallites on the FeAl2O4 impregnated catalyst, despite its lower surface area. The as prepared SCS catalyst contains also a portion of copper as Cu 1+ that increases when subjected to reforming atmosphere. The MSR activity of the SCS catalyst decreases with time-on-stream due to the sintering of catalyst crystallites as established from XPS and HRTEM analyses.

Direct hydrothermal synthesis of mordenite without the addition of both seed and organic template is reported in this work. The role of inorganic cations in the crystal purity and directing the mordenite structure were studied. It was observed that higher Si/Al ratio requires higher alkalinity of the gel. Pure mordenite was obtained using silica gel, colloidal silica and fumed silica. Amorphous material was obtained using tetraethyl orthosilicate (TEOS) due to dissolution problem of TEOS in water. It was also observed that crystal size decrease with decrease in crystallization temperature. The Si/Al ratio can be raised to as high as 50 using silica gel in template-free process. At fixed Na/Si ratio of 0.52, pure mordenite with ratios Si/Al of 15 and 25 could be obtained. fumed silica favours the formation of rod-like crystals.

The thermal behaviour of the Rosa mutiflora biomass by thermogravimetric analysis was studied at heating rate 3 K min À 1 from ambient temperature to 950°C. TGA tests were performed in high purity carbon dioxide (99 998%) with a flow rate 200 ml/min and 100 mg of sample, milled and sieved to a particle size below 250 mm. Moreover, yields of gasification products such as hydrogen (H 2), carbon monoxide (CO) and methane (CH 4) were determined based on the thermovolumetric measurements of catalytic (Ni/Al 2 O 3-SiO 2 and Ni/Al 2 O 3-SiO 2 with K 2 O promoter catalysts) and non-catalytic gasification of the Rosa multiflora biomass. Additionally, carbon conversion degrees are presented. Calculations were made of the kinetic parameters of carbon monoxide and hydrogen formation reaction in the catalytic and non-catalytic CO 2 gasification processes. A high temperature of 950°C along with Ni/Al 2 O 3-SiO 2 and Ni/ Al 2 O 3-SiO 2 with K 2 O promoter catalysts resulted in a higher conversion of Rosa mutiflora biomass into gaseous yield production with greatly increasing of H 2 and CO contents. Consequently, H 2 and CO are the key factors to produce renewable energy and bio-gases (synthesis gas). The parameters obtained during the experimental examinations enable a tentative assessment of plant biomasses for the process of large-scale gasification in industrial sectors.

Climate change and global warming have become a challenging issue affecting not only humanity but also flora and fauna due to an intense increase of CO2 emission in the atmosphere which has gradually led to amplification in the average global temperature. Hence, a number of mechanisms have been promoted to diminish the atmospheric commutation of carbon dioxide. One of the well-known techniques is Carbon Capture and Storage (CCS) which mechanism is based on capture and storage vast quantities of CO2, as well as Carbon Capture and Utilization (CCU) which mechanism is based on CO2 conversion to liquid fuels (e.g. methanol, hydrocarbons, dimethyl carbonate, propylene, dimethyl ether, ethylene, etc.). Particularly, methanol (CH3OH) is a key feedstock for industrial chemicals, which further can be converted into high molecular alternative liquid fuels. In this regard, hydrogenation of CO2 is one of the promising, effectual and economic techniques for utilization of CO2 emission. Neverthel...