Mechanistic insights into the production of methyl lactate by catalytic conversion of carbohydrates on mesoporous Zr-SBA-15

Abstract

The as-synthesized Zr-SBA-15 catalysts with tunable mesoporous structures showed excellent catalytic performance for the conversion of carbohydrates to methyl lactate in a "onepot" process using near-critical methanol or methanol-water mixture as the solvents. The effects of reaction conditions, including temperature, reaction time, and catalyst loading amount, on the conversions of carbohydrates and the yields of methyl lactate were investigated. The high yields of methyl lactate, up to 41 % and 44%, were produced from pentose and hexose, respectively, in the near-critical methanol at 240°C. Moreover, the Si/Zr ratio of the Zr-SBA-15 catalysts profoundly affected the Lewis acidity and therefore the catalytic activity and selectivity to methyl lactate in the conversion of carbohydrates. The pore size of the Zr-SBA-15 catalysts, tuned by the synthesis temperature, strongly affected the formation of solid residues. The key intermediates such as glyceraldehyde, glycolaldehyde, and pyruvaldehyde were used as probe reactants to understand the mechanism. The role of the Zr-SBA-15 catalyst in the aldol-and retro-aldol condensation, isomerization, and Cannizzaro reactions of carbohydrates and their derivatives was discussed. Furthermore, 28% and 27% yields of methyl lactate were obtained from cellulose and starch, respectively, in methanol-water mixture (5 wt% water and 95 wt% methanol) at 240°C. The Zr-SBA-15 catalyst was relatively stable in short term without regeneration.

Hydrogenation of biomass-derived compounds containing a carbonyl group over a copper-based nanocatalyst: Insight into the origin and influence of surface oxygen vacancies

“…Additionally, GBL can be obtained by hydrogenating petroleum-based maleic anhydride over various noble metal and copper-based catalysts [3,4]. With the shortage of fossil resources and increasing emission of greenhouse gases, the conversion from sustainable and renewable raw biomass to useful fuel and chemicals has become more important in the past decade [5][6][7][8][9]. Thanks to the development of biorefinery processes, for example, succinic acid and its derivatives are becoming promising biobased C4 platform molecules for replacing other chemicals such as maleic anhydride [10,11].…”

Fe-Doped SnO2catalysts with both BA and LA sites: facile preparation and biomass carbohydrates conversion to methyl lactate MLA

“…Apart from tin based catalysts, Zr-SBA-15 also showed excellent catalytic performance for the conversion of carbohydrates to MLA. 27 The yields of MLA reached 41% and 44% from pentose and hexose in the near-critical methanol at 240 C. In addition, solid base catalysts, such as hydrotalcites,…”

Catalytic Transfer Hydrogenation of Furfural for the Production of Ethyl Levulinate: Interplay of Lewis and Brønsted Acidities

“…Zr‐SBA‐15 was synthesized according to the procedure described in reference and had been well implemented in our previous articles ,. Briefly, 2 g of Pluronic P123 was added to 75 ml of 1.6 M HCl solution.…”

“…In our previous study,, a detailed characterization of Zr‐SBA‐15 had already been carried out. Based on the pyridine‐DRIFTS results, it had been proved that Zr‐SBA‐15 was predominantly a Lewis acid.…”