The Roles of Precursor-Induced Metal–Support Interaction on the Selective Hydrogenation of Crotonaldehyde Over Ir/TiO2 Catalysts

Various supported Ir/TiO2 catalysts were prepared using different Ir precursors (i.e., H2IrCl6, (NH4)2IrCl6 and Ir(acac)3) and tested for vapor phase selective hydrogenation of crotonaldehyde. The choice of Ir precursor significantly altered the Ir-TiOx interaction in the catalyst, which thus had essential influences on the geometric and electronic properties of the Ir species, reducibility, and surface acidity, and, consequently, their reaction behaviors. The Ir/TiO2-N catalyst using (NH4)2IrCl6 as the precursor gave the highest initial reaction rates and turnover frequencies of crotyl alcohol formation. Such high performance was ascribed to the high Ir dispersion and high surface concentration of Ir0 species, as well as a higher surface acidity, in the Ir/TiO2-N catalyst compared to its counterparts, indicating the synergistic roles of the Ir-TiOx interface in the reaction, as the interfacial sites were responsible for the adsorption/activation of H2 and the C=O bond in the crotonaldehyde molecule.

EFFECT OF OXYGENATED COMPOUNDS ON 1,3-BUTADIENE POLYMERIZATIONS PERFORMED WITH NEODYMIUM VERSATATE. PART I: ALCOHOLS, ALDEHYDES, KETONES, AND WATER

ABSTRACT 1,3-butadiene (1,3-BD) is a building block produced mainly as a byproduct of the ethylene steam cracking process. However, due to the growing interest in sustainable technologies, there is also growing interest in manufacturing 1,3-BD from ethanol. For this reason, taking into account that the ethanol-derived 1,3-BD can contain oxygenated contaminants that are difficult to remove, the present manuscript investigates for the first time how the presence of low concentrations of some oxygenates (acetaldehyde, crotonaldehyde, 3-hydroxybutyraldehyde, acetone, water, ethanol, 1,3-butanodiol, 3-buten2-ol, crotyl alcohol, and 1-butanol) in the 1,3-BD monomer can affect polymerization reactions performed with the neodymium versatate catalyst and modify the characteristics of the obtained polybutadiene products. It is shown that the presence of oxygenated compounds can cause inhibitory effects on the course of the polymerization and modify the molar mass distributions and flow properties of the final products, although all analyzed samples presented the characteristic high-cis character of polybutadienes produced with the neodymium versatate catalyst.

A kinetic and mechanistic study of the osmium(VIII)-catalysed oxidation of crotyl alcohol by hexacyanoferrate(III) in aqueous Alkaline medium

The kinetics and mechanism of the osmium(VIII)-catalysed oxidation of crotyl alcohol by hexacyanoferrate(III) in aqueous alkaline medium is studied. The role of the osmium(VIII) catalyst is delineated to account for the experimental observations. A plausible reaction mechanism is suggested. Activation parameters such as the energy and entropy of activation are evaluated by employing the Eyring equation and are found to be 36.833 kJ mol−1 and −141.518 J K−1 mol−1, respectively.

Selective oxidation of crotyl alcohol by AuxPd bimetallic pseudo-single-atom catalysts

Pseudo single-atom Pd catalysts dispersed in gold nanoparticle matrices show high selectivity and activity for room temperature crotyl alcohol oxidation.

Chemoselective Hydrogenation of –C=O Bond in Multiple Unsaturated Compounds Over Metals Supported on Mesoporous Materials

Liquid-phase hydrogenation of crotonaldehyde in non-polar and polar solvents was studied on monometallic Pd, Pt, Ir, Re catalysts using mesoporous Sibunit and Al2O3 as supports. In the presence of Pd the -C=C- bond of crotonaldehyde was preferably hydrogenated to form butanal, while butanal and crotyl alcohol are formed over Ir catalysts. Crotonaldehyde hydrogenation in 1,4-dioxane did not exhibit further butanal to butanol hydrogenation. Application of Re as a catalyst leads to formation of crotyl alcohol, with activity being, however, twofold lower than of Ir catalysts. Pt/C is almost inactive in the hydrogenation of crotonaldehyde. Formation of crotyl alcohol occurs most efficiently over Ir/Al2O3 in aprotic nonpolar solvents (decane), with selectivity to crotyl alcohol increasing with temperature showing 30% at 25% conversion under 180 °C and hydrogen pressure 0.84 MPa. Crotonaldehyde hydrogenation in a polar protonic solvent (ethanol) results in butanal ac