Room temperature oxidative desulfurization in the presence of new hydrophobic catalysts based on sulfated alumina

Abstract

Herein new hydrophobic molybdenum-containing catalysts based on sulfated alumina were synthesized and applied for room temperature ODS. The synthesized materials were characterized by the following methods: XRF, SEM, TEM, low-temperature N2 adsorption–desorption, FT-IR, TGA, wetting edge angle. Sulfated alumina can be modified with hydrophobic alkylsilanes up to 10 % by weight while maintaining the support structure. The hydrophobic properties of the catalyst are a key factor influencing the efficiency of desulfurization in a biphase system. Octyl-chain modified 10oct/5Mo/S catalyst show significantly better results than propyl-chain 10pr/5Mo/S and unmodified 5Mo/S. Wetting edge angle of 10oct/5Mo/S is 128° and significantly higher than for 10pr/5Mo/S (44.5°) and 5Mo/S (27°). Under the optimized conditions (5.0 mass% of catalyst, H2O2:S molar ratio of 4:1) in presence of 10oct/5Mo/S dibenzothiophene can be completely oxidized in 15 min at room temperature. Under these conditions, the conversion of competitive naphthenic and aromatic hydrocarbon substrates at room temperature does not exceed 4 %, while at 50 ℃ it varies in the range of 12–35 %. For the first time, the possibility of desulfurization of a real diesel fraction at room temperature with a desulfurization degree of 78 % has been demonstrated in the presence of 5.0 mass% of 10oct/5Mo/S, H2O2:S molar ratio of 4:1.