Preparation of mesoporous polyoxometalate-tantalum pentoxide composite catalyst and its application for biodiesel production by esterification and transesterification

One‐Step Preparation of Efficient and Reusable SO42−/ZrO2‐Based Hybrid Solid Catalysts Functionalized by Alkyl‐Bridged Organosilica Moieties for Biodiesel Production

“…The selectivity of the transesterification of Tp with methanol was investigated over SO 4 2À -1.2/ZrO 2 ÀSiO 2 (Et-1.00) and intermediates, including methyl palmitate (MP), dipalmitin, and monopalmitin, were identified by LC-MS. [37] The results suggest that the transesterification of Tp in the current system is a stepwise procedure. It was also found that the conversion of tripalmitate to di-and monopalmitin was complete after 2 h.…”

Zn1.2H0.6PW12O40 Nanotubes with Double Acid Sites as Heterogeneous Catalysts for the Production of Biodiesel from Waste Cooking Oil

“…To solve these problems, heterogeneous heteropoly acids such as Cs salts and supported heteropoly acids have been developed and tested for biodiesel production. [13,14,18] During our studies, we found that the introduction of some Lewis acid ions in heteropolyacid molecules can create Lewis acid sites and their acidity could significantly increase through the coordination of a Lewis acid and a Brønsted acid (unpublished results). Here, we report the preparation of Zn 1.2 H 0.6 PW 12 O 40 (ZnPW) nanotubes templated with cellulose fibers associated with surface sol-gel processes.…”

“…In that case, the conversion reached 90 % at 80 8C in 8 h with a methanol/oil ratio of 30:1. The heteropolyacid catalyst H 3 PW 12 O 40 /Ta 2 O 5 reported by Guo, Clark et al [13] can simultaneously catalyze the esterification of myristic acid and transesterification of tripalmitin with a free fatty acid content of 20 % in the presence of 2 wt % catalyst to give methyl palmitate in 50.7 % yield (65 8C, methanol/oil = 90:1, 6 h).…”

“…Recently, a new strategy of using heteropoly acids as solid acids has been developed by some research groups, [13][14][15][16][17][18] especially 12-tungstophosphoric acid H 3 PW 12 O 40 A C H T U N G T R E N N U N G (HPW), which catalyzes both esterification and transesterification reactions. However, such heteropoly acids act homogeneously only and their catalytic activity is limited by their low surface area (< 10 m 2 g) and the presence of Brønsted acid sites only.…”

Effects of Brønsted and Lewis Acidities on Catalytic Activity of Heteropolyacids in Transesterification and Esterification Reactions

“…Therefore, the design of double acidic site catalysts based on HPAs could open a new field for catalytic applications. Lewis acidity can be introduced by modular grafting of Lewis acidic cations onto the phosphotungstic backbone [23][24][25] or the partial exchange of H + by Lewis cations [22]. In the latter case, Lewis acidity can originate from metal cations as electron pair acceptors, and Brønsted acidity can be generated from the HPA molecules' dissociation of coordinated water under the polarizing effect of the cation [22].…”