Cheng Chang , Frédéric Vogel , Oliver Kröcher , David Baudouin
{"title":"The effect of Ni- and Mo-based materials on thermochemical sulfate reduction by glycerol under hydrothermal process conditions","authors":"Cheng Chang , Frédéric Vogel , Oliver Kröcher , David Baudouin","doi":"10.1016/j.cherd.2024.03.024","DOIUrl":null,"url":null,"abstract":"<div><p>Catalytic hydrothermal gasification (cHTG) is a sustainable and promising route to convert wet biomass into renewable methane, but the catalyst is deactivated by small amounts of soluble sulfate stemming from the biomass feedstock. Under hydrothermal conditions, sulfate can be converted to the strong catalyst poisons thiols or sulfides by thermochemical sulfate reduction (TSR). In this work, we explored the extent to which TSR occurs under conditions relevant to cHTG operation, along with the impact of various materials on the reaction. Our results indicated that within 60 min, an aqueous solution of 20 wt% glycerol and 10 mM potassium sulfate at 25 MPa started to produce organosulfur compounds at ca. 420–440 °C, with yields for the volatile ones of 3% and 6% at 440 °C and 490 °C, respectively. The main products were non-volatile organosulfur compounds (NVOSC), which were tentatively identified as sulfate esters of glycerol or of glycerol decomposition products. A smaller fraction of products consisted of volatile organosulfur compounds (VOSC). The VOSC identified from the TSR with glycerol were mostly alkyl thiophenes, as well as methanethiol, disulfides and trisulfides with no evidence of H<sub>2</sub>S formed. Ni-, Mo-, or NiMo<sub>x</sub>-based materials did not show any catalytic effect on sulfate reduction, independent of the sulfidation of the material. Glycerol was proven to be much more reactive towards TSR than acetone, as no TSR products could be observed when acetone was used as a reducing agent. A reaction pathway for the formation of thiophenes from H<sub>2</sub>S and glycerol is proposed that consists of the dehydration of glycerol, the formation of CO and H<sub>2</sub> from glycerol decomposition, hydroformylation of acrolein, and the Paal-Knorr synthesis with succinaldehyde and H<sub>2</sub>S as intermediates.</p></div>","PeriodicalId":10019,"journal":{"name":"Chemical Engineering Research & Design","volume":null,"pages":null},"PeriodicalIF":3.7000,"publicationDate":"2024-03-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Chemical Engineering Research & Design","FirstCategoryId":"5","ListUrlMain":"https://www.sciencedirect.com/science/article/pii/S0263876224001680","RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q2","JCRName":"ENGINEERING, CHEMICAL","Score":null,"Total":0}
引用次数: 0
Abstract
Catalytic hydrothermal gasification (cHTG) is a sustainable and promising route to convert wet biomass into renewable methane, but the catalyst is deactivated by small amounts of soluble sulfate stemming from the biomass feedstock. Under hydrothermal conditions, sulfate can be converted to the strong catalyst poisons thiols or sulfides by thermochemical sulfate reduction (TSR). In this work, we explored the extent to which TSR occurs under conditions relevant to cHTG operation, along with the impact of various materials on the reaction. Our results indicated that within 60 min, an aqueous solution of 20 wt% glycerol and 10 mM potassium sulfate at 25 MPa started to produce organosulfur compounds at ca. 420–440 °C, with yields for the volatile ones of 3% and 6% at 440 °C and 490 °C, respectively. The main products were non-volatile organosulfur compounds (NVOSC), which were tentatively identified as sulfate esters of glycerol or of glycerol decomposition products. A smaller fraction of products consisted of volatile organosulfur compounds (VOSC). The VOSC identified from the TSR with glycerol were mostly alkyl thiophenes, as well as methanethiol, disulfides and trisulfides with no evidence of H2S formed. Ni-, Mo-, or NiMox-based materials did not show any catalytic effect on sulfate reduction, independent of the sulfidation of the material. Glycerol was proven to be much more reactive towards TSR than acetone, as no TSR products could be observed when acetone was used as a reducing agent. A reaction pathway for the formation of thiophenes from H2S and glycerol is proposed that consists of the dehydration of glycerol, the formation of CO and H2 from glycerol decomposition, hydroformylation of acrolein, and the Paal-Knorr synthesis with succinaldehyde and H2S as intermediates.
期刊介绍:
ChERD aims to be the principal international journal for publication of high quality, original papers in chemical engineering.
Papers showing how research results can be used in chemical engineering design, and accounts of experimental or theoretical research work bringing new perspectives to established principles, highlighting unsolved problems or indicating directions for future research, are particularly welcome. Contributions that deal with new developments in plant or processes and that can be given quantitative expression are encouraged. The journal is especially interested in papers that extend the boundaries of traditional chemical engineering.