Study Of 3DOM Alumina/Titania-based Catalyst For Carbonyl Sulfide Hydrolysis

As the issues of global energy and environmental problem are increasingly prominent,maximizing the utilization of energy as well as reducing environmental pollution have become the key point in during the use of energy.The industrial gases which are made from coal chemical,petrol chemical and natural gas chemical contain a variety of sulfur compounds.The presence of these sulfides will not only cause severe environmental pollution,but also result in the catalyst poisoning in the industrial process.Carbonyl sulfide(COS),as one kind of organic sulfur,is the main form of sulfur.It is difficult to remove due to its stable chemical property.Thus it needs to be transformed into easy-removable hydrogen sulfide firstly.Hydrolysis method is currently the most widely used method for carbonyl sulfur removal.Hydrolysis catalyst mainly include gamma alumina-and titanium oxide-based catalyst,etc.but hydrolysis activity is unstable and can be easily deactivated.Hydrolysate over stay in the catalyst pore is considered to be the main cause of catalyst poisoning.Three-dimensional ordered macroporous(3DOM)materials possess rich ordered macropores,large surface area and interconnection between macropores,thus it can greatly improve the mass transfer of reactants.In recent years,it attracted much attention in the field of gas separation and catalyst because of its unique structural characteristics.This paper is intended to introduce a three-dimensional ordered macroporous(3 DOM)structure into an alumina/titania-based hydrolysis catalyst.The activity and anti-poisoning ability of COS hydrolysis catalytic will be strengthened by improving the mass transfer.This study prepared alumina/titanium oxide hydrolysis catalyst with 3DOM structure by plastic crystal template method.The evaluation of the hydrolysis performance of the catalyst at room temperature was proceed on the micro fixed bed reactor.The oxygen toxicity resistance was also be investigated.X-ray diffraction(XRD),thermogravimetric analysis(TG),differential scanning calorimetry analysis(DSC),nitrogen adsorption and scanning electron microscope analysis(SEM),X-ray photoelectron spectroscopy(XPS),CO2-temperature programmed desorption(CO2-TPD)were used to characterize the catalysts,and the obtained results are shown below.The prepared catalyst possesses complete 3DOM structure,which reveals macroporous-mesoporous-microporous three-level porous structure,macroporous array long-range order and interconnected in three-dimensional space.3DOM alumina catalyst shows y-Al2O3 crystal shape,and 3DOM titanium oxide catalyst shows anatase crystal shape.3DOM structure increases the surface area of alumina-/titanium-based catalysts.The surface area and porosity were increased by adding surfactants P123 in the alumina-based catalyst.The surface area was increased by improving the dispersibility of titanium by adding of SiO2 in titanium-based catalyst.The modification showed above enhances the hydrolysis activity and oxygen toxicity resistance of the catalysts,and the activity of alumina-and titanium-based catalyst were higher than commercial alumina-based hydrolysis catalyst.CO2-TPD characteristic shows that titanium-based catalyst has greater hydrolysis activity than alumina-based catalyst under the same condition because of its greater Lewis basicity and more hydroxyl groups at the surface which is beneficial for the COS hydrolysis of titanium.The oxygen toxicity resistance of titanium-based catalyst was better than alumina-based catalyst for it's weaken adsorption of oxygen on the surface of titanium.It is also found that the main substance causing catalyst poisoning is elemental sulfur under the condition without oxygen in the reaction atmosphere,while elemental sulfur and sulfate both causing catalyst poisoning in the case of containing oxygen.