Preparation Of Catalyst And Research Of Kinetics For Carbonyl Sulfide Hydrolysis Under Moderate Temperature

Carbonyl sulfide (COS), widely existing in the coal gas, petroleumand natural gas, is considered to be a serious poison to many catalystsused in the synthesis process, so it is necessary to remove COS from feedgas like hydrogen sulfide. The hydrolysis of COS with ambient and lowtemperature have been studied over the world, however only fewtechnology has been concentrated on the COS hydrolysis withanti-oxygen-poisoning at moderate temperature till now.This study focuses on developing a novel catalyst of COS hydrolysiswith anti-oxygen-poisoning for moderate temperature. A series ofcatalysts with different catalysts support, support component such as thecontent of vanadic oxide, and pore-making agent were prepared. Thereaction activity and anti-oxygen-poisoning performance of COShydrolysis catalyst were evaluated in a fixed bed reactor. And surfaceproperties of COS hysrolysis catalyst were characterized using thetechnique such as TPD, FTIR, XRD etc. The evaluation results carried out in fixed bed reactor shown that theinitial activity of COS hydrolysis over prepared catalyst is improved bythe increase of the vanadic oxide content; however an overload can belead to a sharply decrease of COS hydrolysis activity at end of reaction,and easily pulverization of catalyst. The most favorable content of vanadicoxide in catalyst is 10wt%. The catalyst performance withanti-oxygen-poisoning can be significantly improved by adding vanadicoxide and using mixed pore-making agents. The conversion of COShydrolysis over modified catalyst can exceed 99% at temperature of 300℃, space velocity of 12000h^-1, COS concentration of 400mgS·m^-3 andO₂ content of 12%.The results of TPD,XRD,FTIR and BET revealed that the oxygenadsorption amount of the catalyst added 10wt% V₂O₅ is the least amongall prepared catalysts, and that of the catalyst added CuO is the most. Theappropriate content of V₂O₅ can increase the conversion of COShydrolysis and reduce the adsorption ratio of H₂S under the presence ofoxygen. There are two CO₂ desorption peak on combination metal oxidecatalyst with different content of vanadic oxide, and the area of the firstdesorption peak on catalyst added 10wt% V₂O₅ is larger than that of thesecond. The area of the first desorption peak decrease with the increase ofV₂O₅ content, The adding V₂O₅ affects the amount and intensity of thesecond basicity center. The second desorption peak area is the largest among all prepared catalysts. And there is no sulfate on the surface ofcatalyst added V₂O₅ after reaction. Loading V₂O₅ could increase theanti-oxygen-poisoning capability of the catalyst. The adding three typespore-making agents, such as CMC, Polyvinyl alcohol and NH₄HCO₃, canincrease the mesopore capacity and surface area of the prepared catalyst.The increase of mesopore may accelerate the diffuseness of H₂S frominside to outside of catalyst, weaken the reaction of H₂S with oxygen.The experiment of COS hydrolysis kinetics indicate that COShydrolysis is first-order reaction for COS and zero-order reaction for H₂O.Kinetics equation is following: r_cos= -dx/(d(W/f_cos,0)=2.83×10⁴P_cose^-22.67/RTReaction mechanism can be concluded that COS is adsorpted on thesurface active center of catalyst, and the surface rate of COS adsorpted iscontrolled step.