|
Methanol is the fundamental raw material of C1chemical industry, which plays animportant role in organic chemical industry. CO in methanol synthesis process not onlyconsumes organic mineral energy, but also produces quantities of CO2, the chemical methodusing CO2as a raw material to replace CO in methanol synthesis reaction has become one ofthe significant technical measures to turn waste CO2into wealth", which has the importanteconomic value and practical significance. This article investigates different conditions on thereaction of methanol synthesis, determine CO2catalyst evaluation conditions. Usingcoprecipitation preparation of CuO/ZnO/Al2O3catalyst, to investigate catalyst compositionand preparation conditions and add fertilizer on the influence law of catalyst activity,selectivity. And through the H2-TPR, XRD, BET to obtain the influence law of catalyticproperties.Within the scope of this paper research, considerating the conversion rate of CO2and theselectivity of methanol. To determine the optimum experiment conditions is250℃,3.0MPa,3600h-1,H2/CO2=3（molar ratio）. In the experiments,CuO/ZnO/Al2O3catalystswhich were prepared by co-precitation method.Under the conditions of Cu/Zn=l（χ）,Al2O3=10%（χ）,Na2CO3as a precipitating, agent in75℃, pH=8, and co-precipitation, aging10h, calcined for4h under350℃,the catalytic properties of catalysts was optimization.Theconversion rate of CO2is20.13%, the selectivity of methanol is31.25%.In theCuO/ZnO/Al2O3catalyst, when adding4%Mn and4%Zr additives respectively,theconversion rate of CO2is24.31%and27.65%, the selectivity of methanol is34.67%and37.81%.Through the characterization methods of H2-TPR, XRD, BET and the performance ofcatalytic reaction, this paper revealed the catalyst composition and preparation conditions and additives on the influence of the catalytic performance. With the increase of Cu/Zn, thereduction temperature increase then decrease, when Cu/Zn/Al=4.5/4.5/1,the highest reductiontemperature is256.4℃, which is difficult to restore, the interaction between Cu and Zn isstrong, the activity of catalyst is high. When Cu/Zn/Al=4.5/4.5/1,the BET specific surfacearea is59.21m2/g. XRD diagram at35.9°appear the CuO and ZnO common characteristicdiffraction peak and the shape of the wide peak is dispersion, Cu and Zn evenly dispersed, theinteraction between Cu and Zn is strong, the activity of catalyst is high.Na2CO3as precipitation agent, XRD diagram at34.5°～36.2°appear the CuO and ZnO commoncharacteristic diffraction peak and the shape of the wide peak is dispersion, Cu and Zn evenlydispersed, the interaction between Cu and Zn is strong, the activity of catalyst is high. As thecalcination temperature increase,calcined under350℃, XRD diagram at35.6ο,36.3ο,48.8οappear the CuO and ZnO common characteristic diffraction peak and the shape of the widepeak is dispersion, Cu and Zn evenly dispersed, the interaction between Cu and Zn is strong,the activity of catalyst is high.Continue to raise the temperature, the diffraction peak is sharpand intensity increase, the specific surface area of catalyst is decreased. Added Mn and ZrBET specific surface area increased from59.21m2/g, respectively to85.44m2/g and92.56m2/g. The XRD spectrum diagram of respectively added Mn and Zr appear the CuO andZnO characteristic peak displacement isn’t shift, which shows that catalyst crystal shape doesnot change, the characteristic diffraction peak width and peak shape of dispersion, Cu and Znis evenly dispersed.
|