Mesoporous (Ta, Nb)3W7 Modified with Stearic Acid Used as Solid Acids for Esterification

Fei Chang,Rui Wang,Hu Pan,Quan Zhou,Heng Zhang

doi:10.1155/2017/9136528

Abstract

Mesoporous solid acids Ta3W7 and Nb3W7 were prepared from TaCl5 and NbCl5 with WCl6 in the presence of stearic acid (SA) via a sol-gel method, respectively. For comparison, mesoporous Ta3W7-P123 mixed oxides and mesoporous Nb3W7-P123 mixed oxides were synthesized in the same way. The catalysts were characterized through TGA, XRD, SEM, TEM, BET, and NH3-TPD. Experimental results showed that Ta3W7-SA and Nb3W7-SA exhibited several advantages such as higher activity, shorter preparation period, lower cost, stronger acid sites, and higher surface area, which had potential to be used as mesoporous heterogeneous catalysts in biodiesel production.

Highlights

Finding an environment-friendly, green, and sustainable energy to substitute fuel has become an urgent issue in the today’s world [1]
The solid acid catalyst is more effective for converting high free fatty acids (FFA) harsh reaction conditions are required in esterification [3,4,5]
In 2013, we investigated the natural calcite and dolomite modified with stearic acid via simple thermal decomposition of the reaction mixtures for preparing a series of solid base catalysts

Summary

Introduction

Finding an environment-friendly, green, and sustainable energy to substitute fuel has become an urgent issue in the today’s world [1]. The solid basemediated process is one of the most commercially useable methods in transesterification to produce biodiesel under mild reaction conditions with high efficiency, but it is quite limited for high acidic oils, CO2, and H2O, and outflow of the catalyst is serious. In 2013, we investigated the natural calcite and dolomite modified with stearic acid via simple thermal decomposition of the reaction mixtures for preparing a series of solid base catalysts. It was demonstrated that the solid base catalysts modified with the templating agents-stearic acid (SA) were environmentally friendly and displayed high catalytic activity for transesterification reactions. The activity of the prepared catalysts was assessed for three high acid value plants oils (Euphorbia lathyris L., Sapium sebiferum L., and Jatropha curcas L.) in esterification reaction. The formation of acidic sites on the catalysts was investigated via the Hammett indicator method, and the optimized reaction conditions were carried out

Experimental

Catalyst Characterization

Esterification

Conclusions