Energy-Saving Dehydration of Primary Alcohol Under the Formation of Alkenes via a Bifunctional Clay Catalyst

Abstract

A commercial acid-leached bentonite (FULCAT®-22 F) catalyzed the dehydration of a range of alcohols efficiently under energy-saving conditions. Dehydration of a primary alcohol such as 1-hexanol took place in the 150–180 °C temperature range with a yield of 52%. This unexpected high catalytic activity was then studied by deeply characterizing the clay catalyst using both fundamental and advanced characterization methods. In agreement with VT-XRD results, by increasing the temperature, BET and PSD analysis evidenced a decrease in SSA (passing from 207 m² g⁻¹ at 180 °C to 175 m² g⁻¹ at 400 °C) and slight modification in the micropores present in the material (0.055 and 0.0039 cm³ g⁻¹ at 180 °C and 400 °C, respectively). EDX showed that Fe, Mg, and K are the most abundant metals present in the structure. A deep spectroscopic analysis, with different basic molecular probes (CO, CD₃CN, Py, and NH₃), revealed, by increasing the temperature, a decrease in Brønsted acid sites and an increase in Lewis acid sites. We hypothesized that the presence of these acidic sites is a key factor contributing to the observed high reaction yield of this clay-type catalyst.