Effect of MgO activation conditions on its catalytic properties for base-catalyzed reactions

Analysis and process evaluation of metal dopant (Zr, Cr)-promoted Ga-modified ZSM-5 for the oxidative dehydrogenation of propane in the presence and absence of CO2†

A systematic study of the comparative performances of 4% Ga-, 4% Zr-, and 1% Cr-impregnated H-ZSM-5 catalysts for oxidative dehydrogenation of propane in the presence and absence of CO₂ is presented. It was found that methane, ethene, propene, butene, pentene, and BTX are the major products from all of these catalysts at various reaction temperatures (400–550 °C), WHSV, 4 kg_cat s mol_C3H8⁻¹ and feed gas, C₃H₈/N₂ = 2.5/97.5 and C₃H₈/CO₂/N₂ = 2.5/5/92.5; flow rate, 75 mL min⁻¹ under atmospheric pressure for 10 h. The combination of material characterization and catalytic testing revealed that Ga-, Zr-, and Cr-doped H-ZSM-5 are excellent catalysts for this process, helping to achieve around 61% CO₂ conversion. The co-doped Ga/H-ZSM-5 catalysts significantly enhanced the activity (65% propane and 61% CO₂ conversion at 550 °C) among all the tested catalysts, with approximately 100% total selectivity 62% towards BTX and 26% towards propene, but with lower selectivity for methane, ethene, and pentene (i.e., light hydrocarbons). TPR profiles indicated that the redox cycle between Cr(iii)O₆ and Cr(vi)O₄ played an important role in the dehydrogenation of C₃H₆ over Cr/Zr–Ga/H-ZSM-5. CO₂ could oxidize a part of the Cr(iii) species to Cr(vi) species under the reaction conditions used.

A systematic study of the comparative performances of 4% Ga-, 4% Zr-, and 1% Cr-impregnated H-ZSM-5 catalysts for oxidative dehydrogenation of propane in the presence and absence of CO₂ is presented.

Combined Reforming of Clean Biogas over Nanosized Ni–Rh Bimetallic Clusters

The combined steam/dry reforming of clean biogas (CH4/CO2 = 50/50 v/v) represents an innovative way to produce synthesis gas (CO + H2) using renewable feeds, avoiding to deplete the fossil resources and increase CO2 pollution. The reaction was carried out to optimize the reaction conditions for the production of a syngas with a H2/CO ratio suitable for the production of methanol or fuels without any further upgrading. Ni-Rh/Mg/Al/O catalysts obtained from hydrotalcite-type precursors showed high performances in terms of clean biogas conversion due to the formation of very active and resistant Ni-Rh bimetallic nanoparticles. Through the utilization of a {Ni10Rh(CO)19}{(CH3CH2)4N}3 cluster as a precursor of the active particles, it was possible to promote the Ni-Rh interaction and thus obtain low metal loading catalysts composed by highly dispersed bimetallic nanoparticles supported on the MgO, MgAl2O4 matrix. The optimization of the catalytic formulation improved the size and the distribution of the active sites, leading to a better catalyst activity and stability, with low carbon deposition with time-on-stream.

Transfer hydrogenation of cinnamaldehyde with 2-propanol on Al2O3 and SiO2–Al2O3 catalysts: role of Lewis and Brønsted acidic sites

Neither surface Brønsted acidic nor basic sites are involved in the catalytic transfer hydrogenation reaction of cinnamaldehyde with 2-propanol.

Perovskites and metal nitrides as catalysts in the base-catalysed aldol addition of isobutyraldehyde to formaldehyde

Hydroxypivaldehyde represents an important intermediate in the production of neopentyl glycol, which in turn is widely applied in the production of e.g. polyesters, plasticizers, synthetic resin paints and lubricants.

Binary Mg–Fe oxide as a highly active and magnetically separable catalyst for the synthesis of ethyl methyl carbonate

The synthesis of ethyl methyl carbonate (EMC) from dimethyl carbonate (DMC) and diethyl carbonate (DEC) over magnetic binary Mg–Fe oxides.