Multifunctional halloysite and hectorite catalysts for effective transformation of biomass to biodiesel

Halloysite surface was modified with tetrabutylammonium iodide, and then the obtained nanomaterial was used as support for ZnO nanoparticles. After characterization, the nanomaterial was used as a catalyst for fatty acid methyl esters (FAMEs) production. The recyclability of the nanomaterial was also investigated, and the optimization of reaction conditions by the design of experiments approach was performed as well. In addition, the synthesized nanomaterial was tested as a catalyst for FAME production from a series of waste lipids affording biodiesel in moderate to good yields (35-95%), depending on the matrix. To fully exploit the feasibility of clay minerals as catalysts in biodiesel formation, a screening of different clays and clay minerals with different morphologies and compositions, such as sepiolite, palygorskite, bentonite, and hectorite was also performed in the esterification of FFAs (a mixture of 1:1 palmitic and stearic acids). Finally, hectorite, chosen as a model of 2:1 clay minerals, was covalently modified, and tested as a catalyst in the esterification of FFAs.

Automated summary

In this study, Halloysite material was modified and used as a support for ZnO nanoparticles, which were then employed as a catalyst for FAMEs production. The recyclability of the nanomaterial was investigated and reaction conditions were optimized using experimental design approach. A screening of different clay minerals was also performed and Hectorite, chosen as a model 2:1 clay mineral, was covalently modified and tested as a catalyst in the esterification of FFAs.