The role of alcohols on the accessibility of basic =SiO- sites in hybrid silicas for catalytic transesterification

Author(s)

Zapelini, Iago William ; Silva, Laura Lorena ; Cardoso, Dilson

• Document type: Journal article
• Source: Brazilian Journal of Chemical Engineering; v. N/A, p. 8-pg., 2023-06-23.

Abstract

The growing production of renewable fuels such as biodiesel, complementary to petroleum diesel, has intensified the search for heterogeneous catalysts containing basic sites to replace the usual homogeneous ones used in industrial transesterification. In this context, hybrid silicas are promising catalysts because of their basic property due to the presence of siloxy anions in their structure, formed by charge compensation with cetyltrimethylammonium cations (CTA(+)), and easy preparation procedure. Several modifications can be used in their synthesis to increase these silicas' catalytic activity. One of them is the use of alcohols as co-solvent in the reaction mixture of its synthesis, containing different numbers of carbon atoms in the linear chain (ethanol, 1-propanol, or 1-butanol), performed in this work. The hybrid silicas prepared in the presence of these alcohols were characterized to evaluate the role of alcohols on their physicochemical properties. They were also catalytically assessed in the model transesterification of ethyl acetate with methanol. The results showed that as the number of carbons in the alcohol chain used to prepare hybrid silicas increased, the value of the initial specific activity (TOF0) increased by about 85% due to greater accessibility to the catalytic sites. The greater sites accessibility was caused by the particle size reduction and an increase in the porosity of the silicas. (AU)

• FAPESP's process: 16/21033-2 - Preparation and modification of hybrid silica spheres for catalytic transesterification
• Grantee: Iago William Zapelini
• Support Opportunities: Scholarships in Brazil - Master