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• Cu-Mn mixed oxides having a Cu 1.5 Mn 1.5 O 4 spinel phase are synthesized. • Higher Cu doping enhances a redox ability and surface oxygen concentration. • The Cu-Mn mixed oxides show good catalytic activities for production of vanillin. • A reaction mechanism for the vanillin production from lignin is proposed. Alkaline wet oxidation of lignin was performed to study the effect of Cu-Mn mixed oxide catalysts on the production of vanillin at between 120–180 °C using H 2 O 2 as an oxidizing agent. The mixed oxide catalysts were prepared by a sol-gel method with mixing ratios of Cu to Mn between 0.25 and 0.75 and characterized by XRD, XPS, N 2 -physisorption, SEM-EDS, and H 2 -TPR. The XRD and N 2 -physisorption analyses showed a non-stoichiometric spinel structure (Cu 1.5 Mn 1.5 O 4) and a relatively high BET surface area of the mixed oxides compared with pure Cu and Mn oxides, respectively. In addition, the Cu-Mn mixed oxide catalysts exhibited better redox properties and a higher catalytic performance for lignin oxidation to vanillin and other aromatic oxygenates. Higher Cu contents in the mixed oxide catalysts promoted the over-oxidation of vanillin producing vanillic acid along with the formation of more surface oxygen species on the catalyst surface. Finally, a possible reaction pathway for the catalytic conversion of lignin to vanillin was proposed. [ABSTRACT FROM AUTHOR]

Abstract In order to obtain sustainable H 2 , the catalytic steam reforming of acetic acid derived from biomass was performed by using the catalysts modified with basic promoters (Mg, La, Cu, and K). La and K increased the total basicity of Ni/γ-Al 2 O 3 by 30.6% and 93.4%, respectively, which could induce ketonization, producing acetone. In contrast, Mg reduced the number of middle and strong basic sites by 17.2% and improved the number of weak basic sites by 5% for Ni/γ-Al 2 O 3 , which promoted the steam reforming of acetic acid (ca. 100% of H 2 and carbon selectivity at even 450 °C) without ketonization. Moreover, the amount of carbon deposited on Ni/Mg/γ-Al 2 O 3 was 55.1% less than that deposited on Ni/γ-Al 2 O 3. When Cu was employed, the conversion was ca. 60% with less than 70% of H 2 selectivity, at all temperatures considered herein. Highlights • A Ni/γ-Al 2 O 3 modified by basic metals for sustainable hydrogen production in catalytic steam reforming of acetic acid. • Ni/Mg/γ-Al 2 O 3 catalyst presented the best performance for production of hydrogen and suppression of coking. • H 2 and carbon selectivity have achieved 100% in the steam reforming of acetic acid over Ni/γ-Al 2 O 3 modified by Mg. [ABSTRACT FROM AUTHOR]

The catalytic dehydration of a bio-based fatty alcohol was performed using Al2O3 prepared by solvothermal synthesis for selective production of long-chain linear-alpha-olefins (LAO). The effect of the synthesis temperature of alumina precursors on the dehydration of 1-octadecanol (C18H38O) was examined based on the textural properties and Lewis acid–base properties of the catalysts. Amorphous alumina synthesized at 325 °C showed the highest surface area (233.07 m2/g) and total pore volume (1.237 cm3/g) among the catalysts and the best dehydration results: 93% conversion, 62% selectivity of 1-octadecene (C18H36), and 89% LAO purity. This was attributed to the increased Al/O ratio and atomic concentration of surface O in alumina, which were important factors in the catalytic dehydration of 1-octadecanol through the synergistic catalysis of acid–base pairs. The produced bio-based LAO can be key intermediates for synthesis of oxo alcohols and poly-alpha-olefins, as alternatives to petroleum-based LAO to achieve carbon neutrality in chemical industry. [ABSTRACT FROM AUTHOR]

• FAME was produced via the direct conversion of wet algae (various water content). • Lipid extraction seemed to the rate-determining step, and water could improve it. • Promoted interaction between methanol and algae by water content. • FAME production could be catalyzed by FFA derived from the hydrolysis of lipid. • 73.9 wt% of FAME yield was accomplished by the adjustable effect of water. Biodiesel production through direct conversion of wet algae has various advantages (economic feasibility, land use, emission of greenhouse gas, eco-friendly process, etc.). However, the effect of the water content of wet algae has not yet been clearly determined. The effect of water was thus investigated in the present study via the direct conversion of raw algae using sub- or supercritical methanol for sustainable liquid fuel production. To understand the reactions, gas-, liquid-, and solid-phase products were analyzed by various gas or liquid chromatography tools, a high voltage electron microscope, simulated distillate, etc. As a result, in the direct conversion of raw Chlorella sp. KR-1, lipid extraction appeared to be the rate-determining step and water contained in wet algae could improve the lipid extraction. It was found that 25 wt% water content of algae could increase the yields of fatty acid methyl esters at or below temperature of 250 °C, which could be induced from enhanced interaction between methanol and algal lipids by water. Meanwhile, excessive water content (>25 wt%) would cause undue hydrolysis, leading to lower yields of fatty acid methyl ester. Moreover, thermal decomposition and gasification would progress more in the reaction using wet algae than dried algae at higher temperatures (>250 °C). Consequently, the critical impact of water could be optimized by those parameters toward maximizing the yield of fatty acid methyl esters. [ABSTRACT FROM AUTHOR]

HFC-134a, one of the representative hydrofluorocarbons (HFCs) used as a coolant gas, is a known greenhouse gas with high global warming potential. Catalytic decomposition is considered a promising technology for the removal of fluorinated hydrocarbons. However, systematic studies on the catalytic decomposition of HFC-134a are rare compared to those for other fluorinated hydrocarbon gases. In this study, Ga-Al2O3 and S/Ga-Al2O3 catalysts were prepared and the change in their properties post-acid treatment was investigated by X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET), temperature-programmed desorption of ammonia (NH3-TPD), in situ Fourier-transform infrared spectroscopy (FT-IR), scanning electron microscopy combined with energy-dispersive X-ray spectroscopy (SEM-EDS), and X-ray photoelectron spectroscopy (XPS). The S/Ga-Al2O3 catalyst achieved a much higher HFC-134a conversion than Ga-Al2O3, which was ascribed to the promotional effect of the sulfuric acid treatment on the Lewis acidity of the catalyst surface, as confirmed by NH3-TPD. Furthermore, the effect of hydrogen fluoride (HF) gas produced by HFC-134a decomposition on the catalyst was investigated. The S/Ga-Al2O3 maintained a more stable and higher HFC-134a conversion than Ga-Al2O3. Combining the results of the stability test and characterization, it was established that the sulfuric acid treatment not only increased the acidity of the catalyst but also preserved the partially reduced Ga species. [ABSTRACT FROM AUTHOR]