In order to investigate the effect of Ce-doping on the catalysts derived from hydrotalcite-like precursors for carbonyl sulfide(COS) hydrolysis,a series of Zn-Ni-Al-Ce hydrotalcite-like compounds were prepared by co-precipitation method and the catalytic activity of their derived composite oxides were studied at 50 oC.The effect on the structural properties caused by Ce doping was studied by the X-ray diffractometer(XRD),scanning electron microscopy(SEM) and energy dispersive spectrometer(EDS).The catalytic activities results showed that addition of Ce enhanced the catalytic activities significantly,but excessive Ce-doping had a negative effect on COS hydrolysis.XRD,SEM and EDS results illustrated that,compared with the Ce-free sample,the particle size of oxide solids decreased and the degree of dispersion increased due to Ce doping.
A series of coal-based active carbon(AC) catalysts loaded by Fe-Cu,Fe-Cu-Ce and Fe-Cu-La were prepared by the sol-gel method for carbon disulfide(CS2) hydrolysis and their performances for CS2 hydrolysis in a fixed-bed reactor were investigated in this work.The results showed that the kind of rare earth oxide and its content had obvious effect on hydrolysis removal of CS2.The effects of temperature,space velocity,CS2 concentration and O2 concentration were also discussed respectively.Furthermore,the suitable operating conditions were obtained.It was found that the poisoning of hydrolysis active sites could result in the formation of sulfuric acid on the catalyst surface.
A novel type of metal oxide/activated carbon catalyst was prepared by sol-gel method for the hydrolysis of carbonyl sulfide(COS) .The influences of the calcination temperature,additive content(2.5%-10.0%Fe2O3,mass fraction) and the basic density of the activation process were thoroughly investigated.The surface of catalysts was characterized by Boehm titration.The products were characterized by scanning electron microscopy(SEM) ,X-ray diffractometry(XRD) and X-ray photoelectron spectroscopy(XPS) .The results show that catalysts with 2.5%-5.0%Fe2O3 after calcining at 500℃have superior activity.The conversion rate of COS increases with increasing the relative density of basic capacity loaded onto activated carbon(AC) ,and the activity follows the order:KOH>Na2CO3>NaHCO3.Boehm titration data clearly show that the total acidity increases(from 0.06 to 0.48 mmol/g) and the basic groups decrease(from 0.78 to 0.56 mmol/g) after COS hydrolysis and H2S adsorption.The XPS results show that the product of H2S may be absorbed by the interaction with metal compounds and O2 to form sulfate(171.28 eV) and element sulfur(164.44 eV) ,which lead to catalysts poisoning.
