Since the discovery of hydrosilylation in 1947, the reaction has been continuously studied and is found to play an important role in the silicone industry, whose products have become an integral part of our lives today. Karstedt’s catalyst is a homogeneous Pt complex reported in the 70’s and has been used for hydrosilylation since then. It was long desirable to develop heterogeneous catalysts that are reusable, easy to separate, and highly active. Since 2000’s, heterogeneous catalysts with high activity and having excellent recyclability have been reported. Their activities are comparable with those of the currently used homogeneous catalyst. In particular, innovative catalysts such as the MOF immobilized complex and the single atom catalyst have been reported. Active species in these catalysts are precisely designed at the molecular or atomic level on surface, and all exhibit extremely high activity for hydrosilylation. In addition to these reports, rhodium complexes grafting on silica have been reported. The grafted Rh complex shows cooperative catalysis with an organic functionality.
Aiming at the production of alternative fuels and chemicals from lipids, deoxygenation of lipids in the catalytic cracking process was investigated. From the catalytic cracking experiments using a saturated triglyceride as feedstock, it was confirmed that deoxygenation as H2O predominantly proceeds despite the introduction of no external hydrogen. The H2O formation can be attributed to hydrogen transfer reaction that proceeds during the catalytic cracking reaction. Furthermore, the deoxygenation as H2O by hydrogen transfer reaction proceeds in preference to the hydrogenation of olefins, which suggests that both suppression of carbon loss during the deoxygenation and production of high value-added hydrocarbons can be achieved by accelerating hydrogen transfer reaction in the catalytic cracking of lipids. Besides, the effects of the unsaturation degree and the molecular structure of feedstocks on catalytic cracking and deoxygenation are examined, and it was confirmed that the optimization of these indexes results in the acceleration of deoxygenation as H2O with suppressing the formation of undesirable polycyclic aromatic hydrocarbons. These findings are expected to contribute to the development of inexpensive and efficient hydrocarbon fuel production technology from lipids using the fluid catalytic cracking process.
Solid base BaO–Al2O3 catalyst was synthesized using the solid-liquid interface reaction of Ba(OH)2 · H2O in the solid phase with Al(OCH(CH3)2)3 dissolved in ethyl acetate. Water of crystallization in the barium hydroxide, Ba(OH)2 · H2O was consumed by hydrolysis of Al(OCH(CH3)2)3 into Al2O3 and isopropanols. BaO–Al2O3 catalyst synthesized by solid-liquid interface reaction of Ba(OH)2 · H2O with equal mols of Al(OCH(CH3)2)3 and heat-treated at 673 K showed the highest activity among the prepared catalysts for the retro-aldol reaction of diacetone alcohol. Active BaO–Al2O3 catalysts with various contents of BaO were obtained by heating at appropriate temperatures just below those of Ba5Al2O8 and BaAl2O4 crystallization. X-ray diffraction analysis detected no BaO phase in this solid base catalyst. Barium oxide highly dispersed in amorphous Al2O3 was prepared by the solid-liquid interface reaction. The interface reaction of metal hydroxide in the solid phase with alkoxide in the liquid phase is useful to form well-dispersed mixed metal oxides.
With the goal of developing a method for utilizing reactive nitrogen species emitted from combustion processes as raw materials for the synthesis of useful compounds, we investigated the selective conversion of NOx to NH3 by means of the NO–CO–H2O reaction over Pt/TiO2 catalysts. High NH3 selectivity was obtained for high-specific-surface-area catalysts. Catalytic activity tests revealed that the activities of catalysts depended on the crystal structure of the support. Comparing CO conversion between NO–CO–H2O reaction and CO–H2O reaction, which could play a role of H-supply reaction, Pt/TiO2 exhibited higher CO conversion for the NO–CO–H2O reaction than that for CO–H2O reaction except for high-surface-area anatase TiO2-supported catalyst around 200 °C. We focused on how the chemical and physical properties of the catalyst surface. Specifically, we carried out temperature-programmed desorption of CO2, which revealed that the CO2 formed during the NO–CO–H2O reaction had no effect on the difference in activity. Carbonaceous surface species and NHx species were observed on the surface of Pt/TiO2 catalyst during NO–CO–H2O reaction by diffused reflectance infrared Fourier transform spectroscopy, and difference in formate formation on anatase-TiO2 supported Pt catalyst was confirmed compared to rutile-TiO2 supported Pt catalyst. We supposed that the difference in activity between anatase and rutile TiO2 was caused by behavior of formate formation.
A logistic function was applied to analyze the synthesis of MFI-type silicalite from raw materials with different sodium hydroxide/quartz ratios. A linear equation (f(t) = at + b), a square-root equation (f(t) = a√(t) + b), and a logarithmic equation (f(t) = aln(t) + b) were used, all of which were functions of synthesis time. Parameters a and b were determined by the least-squares method. Using the logarithmic function (f(t) = aln(t) + b) gave the highest correlation with the experimental results. The slope, a, was almost independent of the synthesis conditions, whereas the intercept, b, varied greatly. In addition, the values obtained for the length of the induction period and the crystal growth rate using the calculated parameters were in good agreement with the experimental results.