The Study On The Performance Of MoP-based Catalysts In Methyl Mercaptan Synthesis From High H₂S-Containing Syngas

This work was prepared out of MOP/Al2O3 and MoP catalysts, molybdenum phosphide-based catalyst to add potassium will be applied to the synthesis of methyl mercaptan from high H2S-containing syngas.The effects of different potassium content of the catalysts, catalyst preparation and synthesis process conditions on the catalytic activitywere investigated. The catalysts were characterized with XRD, H2-TPR, LRS, BET, ESR and XPS to analyze the components of the catalyst structure, and discussed the structure-activity relationship, while optimizing the synthesis conditions. The results of the dissertation were concluded as follows:① For load type MOP/Al2O3 catalyst was added, the amount of potassium additives have a greater impact on the activity of the catalyst, TPR spectra showed K additives added to the catalyst reduction temperature and the amount of H2 in the H2 reduction process have caused great influence, add a small amount of potassium in the catalyst due to the addition of potassium molybdenum weaken the interaction between the species and the carrier Al2O3, thus contributing to the reduction of Mo, get more low-cost molybdenum species; add potassium lot more difficult to restore the catalyst surface potassium molybdate generation, so reducing the temperature rises, reducing the amount of reduction, molybdenum species dispersed more conducive to the improvement of catalytic activity after the restore. LRS spectra detected a large number of add potassium catalyst surface after vulcanization has a lot of Mo-S bond occurs, these lively easier and sulfur species adsorbed on the cheap coordinatively unsaturated Mo of CO generated intermediate transition [COS]≠ species, the[COS]≠ surface species and active hydrogen species continue to react methyl mercaptan, potassium Promotors show favor the formation of active catalyst surface molybdenum sulfur species, thereby contributing to the generation of methanethiol. XRD detected K2SO4 crystals also indirectly illustrates this point. Activity evaluation results show that adding potassium phosphate molybdenum based catalyst additives can effectively improve the catalyst activity. With the aid of potassium content of increase KxMoP/ Al2O3 catalyst activity exhibited first and then decreased the law, show that adding an appropriate amount of potassium aid advantageous for the reaction, which K2.5MoP /Al2O3 catalyst has the best catalytic activity A selectivity and conversion of carbon monoxide mercaptan were:24.74% and 29.05% [as long as the CO conversion and selectivity of methyl mercaptan. Catalysts for the process conditions in the final reduction temperature, and phosphorus content, carriers and additives are optimized screening results show that reducing the final temperature, and phosphorus content, and the availability of carrier catalyst in the reaction of the additive have a greater impact, in which 850℃ final temperature reduction, P:Mo=1:1 phosphorus content, activated alumina carrier,500℃ calcination temperature, citric acid additives on the reaction more favorable. The reaction conditions for the synthesis of high-sulfur syngas to methyl mercaptan in the reaction temperature and feed gas hydrogen sulfide content optimized screening results show that the reaction temperature and feed gas hydrogen sulfide content of the catalyst in the reaction are compared impact, wherein the reaction temperature of 380 ℃ and CO:H2:H2S=1:1:2 hydrogen sulfide content of the reaction more advantageously.② For MoP catalyst precursor phase, the amount of potassium additives have a greater impact on the activity of the catalyst, XRD detected K2SO4 crystals also shows molybdenum phosphide catalysts in curing a lot of lively young man became advantageous methyl mercaptan sulfur species generate. Activity evaluation results show that adding potassium phosphate molybdenum based catalyst additives can effectively improve the catalyst activity. With the aid of active potassium content of increase KxMoP catalysts exhibit first and then decreased the law, show that adding an appropriate amount of potassium aid advantageous for the reaction, which K1.5MoP catalyst has the best catalytic activity, select the methyl mercaptan and carbon monoxide conversion rates were:15.92% and 15.53% [as long as the CO conversion and selectivity of methyl mercaptan]. Process conditions the catalyst prepared baking temperature is optimized screening results showed that the calcination temperature of the catalyst in the reaction have a greater impact, wherein the reaction temperature of 500 ℃ firing more favorable. The reaction conditions for the synthesis of high-sulfur syngas to methyl mercaptan in the gas hourly space velocity and gas pressure were optimized screening results show that the gas pressure and gas hourly space velocity of the catalyst in the reaction have a greater impact, which is GHSV gaseous space velocity of 3000h-1 and the reaction gas pressure of 0.2 MPa more favorable.