Sulfated Zirconia Synthesized in a One Step Solvent-Free Method for Removal of Olefins from Aromatics

Abstract

Sulfated zirconia was synthesized by a one step solvent-free method, directly mixing Zr­(OH)4 and (NH4)2SO4. The entire synthesis process produces no wastewater, which is environmentally friendly. The synthesis factor (mole ratio of (NH4)2SO4:Zr­(OH)4) is the main point to test catalytic activity. Structural properties are characterized by X-ray diffraction (XRD), N2 adsorption–desorption isotherms, and inductively coupled plasma (ICP). The acid property is characterized by pyridine-FTIR. The S coverage (×10–6 mol S·m–2)–Lewis acidic sites density (mmol·m–2) relationship in sulfated zirconia reveals that the generation order of Lewis acidic sites is from weak ones to strong ones. Calculation of acid property reveals the positive structural–functional relationship (WL/SL–catalytic activity). Weak Lewis acidic sites (WL) promote the activity toward removal olefins, while strong Lewis acidic sites (SL) speed up the deactivation of catalysts. The superior catalytic performance as well as environmentally friendly synthesis method demonstrates that solvent-free sulfated zirconia has bright application prospects in industry.

Metal‐reinforced sulfonic‐acid‐modified zirconia for the removal of trace olefins from aromatics

“…For AlMSZ‐923 and AlMSZ‐823, the increase in calcination temperature generated weak effects on the phase; the t‐ZrO 2 phase of AlMSZ‐923 was only 4% higher than that of AlMSZ‐823. Based on the studies of sulfated zirconia, t‐ZrO 2 was considered beneficial for the reaction in removing trace olefins from aromatics 32,33 . For ZnMSZ, the increase of calcination temperature caused the decrease of t‐ZrO 2 in these catalysts, and the calcination temperature of 823 K was better, as the excessively high calcination temperature had a giant influence on the crystal form of the catalyst.…”

“…In recent years, solid superacids, especially sulfated zirconia, have been widely used in alkylation, 17,18 isomerization, 19–21 esterification, 22 and dehydration 23 . A novel one‐step solvent‐free method to synthesize sulfated zirconia was reported by Liu et al 24 However, due to the weak bond between the sulfate groups and zirconia and the few active sites on the zirconia surface, the catalytic activity of this sulfated zirconia was unsatisfactory. Besides, sulfuric acid would inevitably corrode the equipment during the preparation of sulfated zirconia and is often accompanied by water pollution, soil acidification, acid rain, and so on.…”

Heat treatment induced phase transformations in zirconia and yttria-stabilized zirconia monolithic aerogels

“…It has been studied for several applications in catalysis, in engineering as a structural material and as a semiconductor. [7,8] In order to improve the performance of ZrO2-based materials, a high surface area and the phase stability of zirconia are desirable characteristics. Pure ZrO2 is a polymorphic oxide that has three well-known thermodynamically stable crystalline phases: i) the monoclinic phase (m-ZrO2) which is stable from room temperature to 1170 °C, ii) the tetragonal phase (t-ZrO2) which is stable between 1170 and 2370 o C and iii) the cubic (c-ZrO2) phase exists between 2370 and 2680 °C.…”

Selection of suitable bentonite and the influence of various acids on the preparation of a special clay for the removal of trace olefins from aromatics

“…Petroleum processing produces aromatic streams containing benzene, toluene and xylene during reforming and cracking processes. The production of these compounds is accompanied by the production of undesirable olefins that can be harmful to downstream units and poison their catalysts (Liu et al, 2017;Wang et al, 2021).…”

“…Two processes are typically used for the removal of olefins from aromatic streams: (1) clay treating and (2) catalytic hydrotreating (Liu et al, 2017;Guo et al, 2020). In catalytic hydrotreating, olefins are saturated during the hydrogenation reactions on selective hydrogenation catalysts.…”