Improving the Performance of BaMnO3 Perovskite as Soot Oxidation Catalyst Using Carbon Black during Sol-Gel Synthesis

A series of BaMnO3 solids (BM-CX) were prepared by a modified sol-gel method in which a carbon black (VULCAN XC-72R), and different calcination temperatures (600 °C–850 °C) were used. The fresh and used catalysts were characterized by ICP-OES, XRD, XPS, FESEM, TEM, O2-TPD and H2- TPR-. The characterization results indicate that the use of low calcination temperatures in the presence of carbon black allows decreasing the sintering effects and achieving some improvements regarding BM reference catalyst: (i) smaller average crystal and particles size, (ii) a slight increase in the BET surface area, (iii) a decrease in the macropores diameter range and, (iv) a lower temperature for the reduction of manganese. The hydrogen consumption confirms Mn(III) and Mn(IV) are presented in the samples, Mn(III) being the main oxidation state. The BM-CX catalysts series shows an improved catalytic performance regarding BM reference catalyst for oxidation processes (NO to NO2 and NO2-assisted soot oxidation), promoting higher stability and higher CO2 selectivity. BM-C700 shows the best catalytic performance, i.e., the highest thermal stability and a high initial soot oxidation rate, which decreases the accumulation of soot during the soot oxidation and, consequently, minimizes the catalyst deactivation.

Green Synthesis and Characterization of a ZnO-ZrO2 Heterojunction for Environmental and Biological Applications

The zinc oxide–zirconium dioxide (ZnO-ZrO2) heterojunction was prepared by a green method using rubber leaves as reducing and capping agents. Various physicochemical techniques were used to study the chemical composition and the structural and optical properties of the synthesized nanocomposite. The nature of the heterojunction was confirmed through X-ray diffraction and the average sizes of ZnO and ZrO2 crystallites were found to be 70 and 24 nm, respectively. The photocatalytic potential of the ZnO-ZrO2 heterojunction was examined against rhodamine 6G (Rh-6G), and 97.30 percent of the dye was degraded due to the synergistic effect of the light and the catalyst. The commercial ZnO nanopowder was used as a reference catalyst and 86.32 percent degradation was noted under the same reaction conditions. The in vitro antioxidant activity was also performed to scavenge the 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) free radicals, where the activity of the ZnO-ZrO2 heterojunction was found to be higher than the ascorbic acid.

Hydrogenation of Nitro Compounds over Catalytic Systems Containing Rare-Earth Oxides

The paper studies the activity of 1 % palladium catalysts containing rare earth oxides (REOs) and alumina as a carrier in the hydrogenation of nitro compounds exemplified by nitrobenzene and o-nitro anisole. Under the liquid-phase hydrogenation conditions, these catalytic systems provide high selectivity of the process and a quantitative yield. It has been found that the partial replacement of Al2O3 with REO allows increasing the hydrogenation rate by 5–6 times, as compared with the reference catalyst and by 1.2–1.7 times as compared with the individual carrier. The oxide mixtures (REO and Al2O3) containing 20–40 % REO allow reaching the same hydrogenation rate with that over an REO-containing 1 % Pd catalyst.

Hydrodesulfurization of dibenzothiophene using NiMoWS catalysts supported on Al–Mg and Ti–Mg mixed oxides

In this work, two series of trimetallic NiMoW sulfide catalysts supported on Al–Mg(x) and Ti–Mg(x) mixed oxides with different content of MgO (x = 5, 10, 15 and 20 wt.% of MgO) were synthesized. The mixed oxides and catalysts were characterized by X-ray diffraction (XRD), Fourier-transform infrared (FT-IR) spectroscopy, N2 physisorption and Diffuse reflectance spectroscopy (DRS UV–Vis); and evaluated during the hydrodesulfurization (HDS) of dibenzothiophene (DBT) reaction. The NiMoW/Al–Mg catalysts showed a higher dispersion of Ni, Mo and W species than NiMoW/Ti–Mg catalysts resulting in higher catalytic activities. Catalysts with 10 wt.% of MgO showed the highest catalytic activity for both series of catalysts. Most of the synthesized catalysts exhibited higher activities than NiMoWS/Al–Ti reference catalyst. The present comparison study clearly showed that NiMoW/Al–Mg and NiMoW/Ti–Mg catalyst with 10 wt.% of MgO might be a promising and effective catalyst for the HDS-DBT reaction.

Biogas Upgrading Via Dry Reforming Over a Ni-Sn/CeO2-Al2O3 Catalyst: Influence of the Biogas Source

Biogas is a renewable, as well as abundant, fuel source which can be utilised in the production of heat and electricity as an alternative to fossil fuels. Biogas can additionally be upgraded via the dry reforming reactions into high value syngas. Nickel-based catalysts are well studied for this purpose but have shown little resilience to deactivation caused by carbon deposition. The use of bi-metallic formulations, as well as the introduction of promoters, are hence required to improve catalytic performance. In this study, the effect of varying compositions of model biogas (CH4/CO2 mixtures) on a promising multicomponent Ni-Sn/CeO2-Al2O3 catalyst was investigated. For intermediate temperatures (650 °C), the catalyst displayed good levels of conversions in a surrogate sewage biogas (CH4/CO2 molar ratio of 1.5). Little deactivation was observed over a 20 h stability run, and greater coke resistance was achieved, related to a reference catalyst. Hence, this research confirms that biogas can suitably be used to generate H2-rich syngas at intermediate temperatures provided a suitable catalyst is employed in the reaction.

Kinetics of Dicyclopentadiene Hydroformylation over Rh–SiO2 Catalysts

The hydroformylation of dicyclopentadiene (DCPD) to monoformyltricyclodecenes (MFTD) represents a key intermediate step in the conversion of the C5 fraction derived from the petrochemical process to value-added fine chemicals, for example, diformyltricyclodecanes and tricyclodecanedimethylol. Although both heterogeneous and homogeneous catalysts can catalyse this reaction, the heterogeneously catalysed pathway has received significantly less attention due to its lower catalytic activities. We demonstrate in this work that a low Rh loaded heterogeneous 0.1% Rh–SiO2 catalyst can present a similar performance relative to the homogeneous Rh(PPh3)Cl, a reference catalyst for this reaction. Furthermore, an extensive kinetic study of DCPD hydroformylation to MFTD using heterogeneous 0.1% Rh–SiO2 catalysts has been performed. A series of kinetic experiments was carried out over a broad range of conditions (temperature: 100–120 °C; pressure: 1.5–5 MPa; catalyst-to-reactant mass ratio: 0.02–0.05; PPh3 concentration: 5–12.5 g L−1). A kinetic analysis was carried out, indicating the activation energy for the reaction to be 84.7 kJ mol−1. DCPD conversion and MFTD yield could be optimised to be as high as 99% at 0.1% Rh loading, a DCPD/catalyst mass ratio of 25, a PPh3 concentration of 10 g L−1, a reaction time of 4 h and a reaction pressure of 4 MPa.

One-Pot Isomerization of n-Alkanes by Super Acidic Solids: Sulfated Aluminum-Zirconium Binary Oxides

Super acidic nanostructured sulfated aluminum-zirconium binary oxides in mole ratios of Zr4+: Al3+ as 2:1 (SAZ-1), 1:1 (SAZ-2), 1:2(SAZ-3) and the reference catalyst super acidic sulfated zirconia (SZ) were synthesized by a precipitation method. Firstly, the catalytic performance of these four catalysts was evaluated during the isomerization of n-hexane to 2-methyl pentane and 3-methyl pentane, n-heptane and n-octane to their corresponding branched chain isomers at low temperature and pressure conditions (40°C and 1 atm). SAZ-1 performed the highest active and selective isomerization of n-hexane, n-heptane, and n-octane into their corresponding branched chain isomers. The catalytic activity of the reference catalyst SZ was the lowest among the four synthesized catalysts. TEM analysis applied to SAZ-1 and SZ indicated the presence of particle-bulks having average size of 20 nm; moreover, these materials presented an amorphous nature, having no particular surface morphology. XRD confirmed the amorphous structure of SAZ-1 and SZ as well as indicated their internal phase structure. FTIR generated ideas about different linkages and bond connectivities between atoms and groups in SAZ-1 and SZ. Ammonia-TPD of these two materials confirmed the higher super acidic nature of SAZ-1 and lower super acidic nature of SZ. Catalyst evaluation and characterization allowed to propose a reaction mechanism, elucidating a possible role of Brønsted and Lewis acid sites on the studied reaction-catalyst, being the former active sites the main factor leading to isomerization reaction. AFM and SEM pictures indicated the nature of the surface of the catalysts. Nevertheless, SEM analysis before and after the reaction displayed that catalyst morphology was modified and could influence the activity of the catalyst. The use of SAZ-1 is cost saving as well as energy saving.

Synthesis and application of a porous composite material synthesized via an in situ technique

Novel composite materials with wide pores were synthesized by an in situ technique using kaolin, palygorskite and pseudoboehmite as raw materials. The characterization results indicated that the synthesis components and conditions influenced the micro-, meso- and macro-porosity of the composite materials. The composites contained 53.5% zeolite Y and had much larger specific surface areas and pore volumes as well as significant hydrothermal stability. Fluid catalytic cracking (FCC) catalysts were prepared based on the composite materials. The results indicated that the as-prepared catalysts possessed a unique pore structure which assisted in diffusion-controlled reactions. In addition, the attrition resistance, activity and hydrothermal stability of the catalyst studied were superior to those of a reference catalyst. The catalyst studied also exhibited excellent nickel and vanadium passivation performance, strong ‘bottoms upgrading’ selectivity and better gasoline and coke selectivity.

Study on a Novel Prerefining Catalyst for Hydrocracking Process

The effect of different promoters and the content of promoters on the hydrorefining catalyst for hydrocracking process were studied. The results showed that specific promoter can effectively change the properties of carriers, which resulted in the catalysts have large surface area, high activity,and suitable acidity. When the content of promoter was three percent, the catalyst had the best performance. The evaluation results revealed the reaction temperature of developped catalyst was lower 6°C than that of the reference catalyst on the condition of obtaining the same products.

Catalytic Combustion of Waste Palm Trunk Derived Biochar and Biomass

The evaluation of catalytic combustion of waste palm trunk derived biomass and biochar with perovskite supported by K2CO3 using the TG (thermogravimetric) under oxidation atmospheres was carried out. Catalyst activity system of K2CO3 supported on perovskite was studied. The effect of using developed catalyst and reference catalyst in the catalytic combustion of waste palm trunk derived biomass and biochar was investigated. Catalysts, biomass and biochar waste palm trunk samples separated into the size of 100μm to 250μm fractions were subjected to non-isothermal thermogravimetric experiments were performed with different atmospheres which consisted of nitrogen and oxygen with N2:O2 9:1 ratio, at heating rate of 2°C/min in the presence of 100cc/min total flow of N2 and O2. Alumina, K10Alumina and Ni10Alumina catalysts showed very poor catalytic combustion activity. However K10LMC82 or K2CO3/LaMn0.8Cu0.2O3 catalyst showed better catalytic combustion activity compared to the other catalysts, which indicated that perovskite oxide was more effective as a support for the combustion.