The selective N-methylation of bifunctionalized amines with supercritical methanol (scCH(3)OH) promoted by the conventional solid acids (H-mordenite, beta-zeolite, amorphous silica-alumina) and acid-base bifunctional catalysts (Cs-P-Si mixed oxide and gamma-alumina) was investigated in a continuous-flow, fixed-bed reactor. The use of scCH(3)OH in the reaction of 2-aminoethanol with methanol (amine/CH(3)OH = 1/10.8) over the solid catalysts led to a significant improvement in the chemoselectivity of the N-methylation. Among the catalysts examined, the Cs-P-Si mixed oxide provided the most efficient catalyst performance in terms of selectivity and reactivity at 300 degrees C and 8.2 MPa; the N-methylation selectivity in the products reaching up to 94% at 86% conversion. The present selective methylation was successfully applied to the synthesis of N-methylated amino alcohols and diamines as well as O-methylated ethylene glycol. Noticeably, ethoxyethylamine was less reactive, suggesting that the hydroxy group of the amino alcohols is a crucial structural factor in determining high reactivity and selectivity, possibly because of the tethering effect of another terminus, a hydroxo group, to the catalyst surface. The magic-angle-spinning NMR spectroscopy and X-ray diffraction analysis of the Cs-P-Si mixed oxide catalyst revealed that the acidic and basic sites originate from P(2)O(5)/SiO(2) and Cs/SiO(2), respectively, and the weak acid-base paired sites are attributed to three kinds of cesium phosphates on SiO(2). The weak acid-base sites on the catalyst surface might be responsible for the selective dehydrative methylation.

A novel continuous-flow scCO(2) process for kinetic resolution of racemic alcohols can be performed with an immobilized lipase to lead to a quantitative mixture of the corresponding optically active acetates with up to 99% ee and unreacted alcohols with up to 99% ee, in which the productivity of the optically active compounds was improved by over 400 times compared to the corresponding batch reaction using scCO(2).

Although bio-oils produced by pyrolysis and hydrothermal synthesis demonstrate potential toward building a sustainable society, large amounts of char generated as a byproduct and their thermal instability owing to high oxygen content hinder their applications. Hence, a novel approach for the production of high-grade bio-oil was proposed herein. In this approach, zerovalent Fe was used as an agent for generating hydrogen in situ in the hydrothermal liquefaction of oil palm empty fruit bunch (EFB), a lignocellulosic biomass source, affording bio-oil containing water-soluble (WS) and water-insoluble (WI) fractions in high yields. Hydrogen generated by the reaction between Fe and H2O efficiently converted unstable intermediates obtained from the degradation of EFB into stable compounds, resulting in reduced char formation. Hydroxyketones were detected as components characteristic of the WS fraction in the H2O/EFB/Fe system, which were stable under hydrothermal condition. WS fractions were treated with the HZSM-5 zeolite, affording light olefins (C2–C4), as well as benzene, toluene, and xylene. This conversion was more efficient with the WS fraction obtained in the presence of Fe. The liquefaction of EFB and the conversion of WS fractions into olefins via catalytic cracking were also achieved using recycled Fe.

Abstract:The chemoselective methylation of mcresol and phenol with supercritical methanol (scCH 3 OH) promoted by metal oxide catalysts (MgO, ZrO 2 , Cs À P À Si and Fe À V/SiO 2 ) was investigated in a continuous flow fixed bed reactor. The use of scCH 3 OH as a carrier medium led to a significant change in the product selectivity compared to that attained in the gas phase reaction, and caused a marked suppression of the degradation of CH 3 OH during the reaction, resulting in an improvement in the catalyst lifetime. The chemoselective outcome of the reaction was highly influenced by the acidbase character on the solid catalysts examined under supercritical conditions.