Catalysts2015, 5(4), 2024-2038; doi:10.3390/catal5042024 - published 24 November 2015 Show/Hide Abstract
Abstract: WO3 vertical plate-like arrays provide a direct pathway for charge transport, and thus hold great potential as working electrodes for photoelectrochemical (PEC) water splitting. However, surface recombination due to surface defects hinders the performance improvement. In this work, WO3 vertical plate-like arrays films with HfO2 passivation layer were fabricated via a simple dip-coating method. In the images of transmission electron microscope, a fluffy layer and some small sphere particles existed on the surface of WO3 plate. X-ray photoelectron spectroscopy (XPS) showed a higher concentration of Hf element than the result of energy-dispersive X-ray spectroscopy (EDX), which means that HfO2 is rich on the surface of WO3 plates. A higher photocurrent under visible light irradiation was gained with surface passivation. Meanwhile, the results of intensity modulated photocurrent spectrum (IMPS) and incident photon to current conversion efficiency (IPCE) indicate that HfO2 passivation layer, acting as a barrier for the interfacial recombination, is responsible for the improved photoelectrochemical performance of WO3 vertical plate-like arrays film.
Catalysts2015, 5(4), 2018-2023; doi:10.3390/catal5042018 - published 24 November 2015 Show/Hide Abstract
Abstract: Catalysis is a critical scientific field that underpins much of the world’s chemical industry. For example, it is often quoted that catalysis plays a role in 90% of all industrial chemical products. This importance has led to numerous academic journals and specialized conferences on the subject, as practitioners seek outlets to publish their cutting-edge research on catalysis. [...]
Catalysts2015, 5(4), 2001-2017; doi:10.3390/catal5042001 - published 20 November 2015 Show/Hide Abstract
Abstract: In general, ethylene/1,3-butadiene copolymerizations provides copolymers possessing both pendant vinyls and vinylenes as olefinic moieties. We, at MCI, studied the substituent effects of C2-symmetric zirconocene complexes, rac-[Me2Si(Indenyl’)2]ZrCl2 (Indenyl’ = generic substituted indenyl), after activation on the ratio of the pendant vinyls and vinylenes of the resultant copolymers. Complexes examined in this study were rac-dimethylsilylbis (1-indenyl)zirconium dichloride (1), rac-dimethylsilyl-bis[1-(2-methyl-4,5-benzoindenyl)] zirconium dichloride (2), rac-dimethylsilyl-bis[l-(2-methyl -4-phenylindenyl)]zirconium dichloride (3), rac-dimethy1si1y1- bis(2-ethyl-4-phenylindenyl) zirconium dichloride (4), rac-dimethylsilyl-bis[l-(2-n-propyl -4-(1-naphthyl)indenyl)]zirconium dichloride (5), rac-dimethylsilyl-[1-(2-ethyl-4-(5-(2,2-dimethyl-2,3-dihydro-1H-cyclopenta [a]naphthalenyl)indenyl))][1-(2-n-propyl-4-(5-(2,2-dimethyl-2,3-dihydro-1H-cyclopenta[a] naphthalenyl)indenyl))]zirconium dichloride (6), rac-dimethylsilyl-bis[1-(2-ethyl-4-(9-phenanthryl)indenyl)]zirconium dichloride (7), and rac-dimethylsilyl-bis[l-(2-n-propyl-4-(9-phenanthryl)indenyl)]zirconium dichloride (8). We found that the ratio of the pendant vinyls and vinylenes is strongly affected by the bulkiness of the substituent on the complexes examined. The vinyl content increased linearly in the following order, 8 > 7 > 6 > 5 > 4 > 3 > 2 > 1. Notably, complex 8/DMAO formed ethylene/1,3-butadiene copolymers possessing predominant vinyl groups, which can be crucial precursors for functionalized polyolefins. Likewise, complex 8/DMAO afforded propylene/1,3-butadiene copolymers with predominant vinyl groups.
Catalysts2015, 5(4), 1983-2000; doi:10.3390/catal5041983 - published 20 November 2015 Show/Hide Abstract
Abstract: For the effective production of hydrocarbon liquid fuel in the hydrocracking of the Fischer-Tropsch (FT) product, the catalytic performance of Pt-loaded catalysts with low Pt content was investigated using an autoclave at 250 °C, an initial H2 pressure of 0.5 MPa, and a reaction time of 1 h. A screening study using Pt-loaded catalysts with a Pt content of 0.1 wt. % indicated that zeolite supports were more favorable for jet fuel (carbon numbers 9–15) production than amorphous oxide supports. The small particle size of the supported Pt particles and the high amount of medium acid sites for the supports led to higher performance of the Pt-loaded zeolite catalysts. In the hydrocracking reaction over Pt catalysts using the zeolite support with the high amount of medium acid sites, the yields of the corresponding jet fuel at 0.02 and 0.1 wt. % were almost the same. Pt-loaded catalysts with a Pt content of 0.02 wt. % were prepared using water-in-oil (w/o) microemulsions and their particle size was controlled between 1.0 and 2.6 nm. While the yield of the corresponding jet fuel was independent of Pt particle size, smaller Pt particles typically promoted the production of lighter hydrocarbons.
Catalysts2015, 5(4), 1969-1982; doi:10.3390/catal5041969 - published 19 November 2015 Show/Hide Abstract
Abstract: Rhodium(I)-complex [Rh(CO)2I2−] (1) catalyzed two carbonylations of methyl iodide and trimethylamine in NMP (1-methyl-2-pyrolidone) to acetic acid and DMAC (N,N-dimethylacetamide) in the presence of calcium oxide and water. The carbonylation of trimethylamine continued during the carbonylation and consumption of methyl iodide. In total, 183.8 mmol of carbonylated products was produced while consuming 24.1 mmol methyl iodide via acetic acid formation. These results clearly indicated that there were two carbonylation routes of trimethylamine and methyl iodide and the carbonylation rate of trimethylamine was faster than that of methyl iodide. Rhodium(I)-complex [Rh(CO)2I2]− (1) in the presence of trimethylamine was stable enough to be used 25 times with TON (Turnover Number) of 368 for DMAC and TON of 728 for trimethylamine. Inner-sphere reductive elimination in stepwise procedure was suggested for the formation of DMAC instead of acyl iodide intermediate under anhydrous condition.
Catalysts2015, 5(4), 1948-1968; doi:10.3390/catal5041948 - published 16 November 2015 Show/Hide Abstract
Abstract: A novel methodology is presented for more comprehensive catalyst development by maximizing the acquired information rather than relying on statistical methods or tedious, elaborate experimental testing. Two dedicated high-throughput kinetics (HTK) set-ups are employed to achieve this objective, i.e., a screening (HTK-S) and a mechanistic investigation one (HTK-MI). While the former aims at evaluating a wide range of candidate catalysts, a limited selection is more elaborately investigated in the latter one. It allows focusing on an in-depth mechanistic analysis of the reaction mechanism resulting in so called “kinetic” descriptors and on the effect of key catalysts properties, also denoted as “catalyst” descriptors, on the catalyst performance. Both types of descriptors are integrated into a (micro)kinetic model that allows a reliable extrapolation towards operating conditions and catalyst properties beyond those included in the high-throughput testing. A case study on ethanol conversion to hydrocarbons is employed to illustrate the concept behind this methodology. The methodology is believed to be particularly useful for potentially large-scale chemical reactions.