The Study On Preparation Of Ammonia Composite Adsorbent

In this paper, the law of monolayer dispersion and effects of preparationconditions on carrier structure of CaCl₂ onto cartier were studied by XRD accordingto the theory of spontaneous monolayer dispersion. The effects of different loadmethods, dispersion methods and calcination temperatures on the monolayerdispersion of CaCl₂ onto 10X zeolite and Silica gel were studied. The ammoniaadsorption capacity of composite samples was measured primarily. The preliminaryfoundation was established for the study of ammonia composite adsorbentpreparation.The dispersion result of impregnation samples is better than dry mixture samplesin the dispersion system of CaCl₂/10X and CaCl₂/silica gel. For the system ofCaCl₂/10X, the CaCl₂(0.6g CaCl₂/g10X) can be dispersed completely when thesample impregnated in ethanol solution is calcined at 500℃, but the peaks of crystalCaCl₂ still exist for dry mixture when the load capacities of CaCl₂ are reduced from0.6g/g to 0.4g/g and the samples are calcined at 600℃. For the system of CaCl₂/silica gel, the CaCl₂ peaks of sample preparated by dry mixture are remarkablybigger than the sample impregnated in aqueous solution.For the system of CaCl₂/10X, the fitting load method is by impregnation inethanol solution and the calcination temperature is 500℃. For the system of CaCl₂/silica gel, the fitting load method is by impregnation in aqueous solution andthe range of calcination temperature is from 500℃to 550℃.The skeleton structure of the carder will be changed when the calcinationtemperature is too high for both systems. The skeleton structure of 10X zeolite willbe changed when the sample(CaCl₂/10X) which is impregnated in ethanol solution iscalcined at 600℃. The skeleton structure of silica gel will be changed obviouslywhen the sample(CaCl₂/silica gel) which is impregnated in aqueous solution iscalcined at 600℃.The actual dispersion threshold of CaCl₂ onto 10X zeolite is 0.61g/g which isclose to the theoretical threshold(0.62g/g), and so the coverage of CaCl₂ onto 10Xzeolite can reach 98%. The actual dispersion threshold of CaCl₂ onto silica gel is0.31g/g which is more less than the theoretical threshold (0.4g/g), and so thecoverage of CaCl₂ onto silica gel can reach 77%. The energy and geometricfavorable position of silica gel is apt to the dispersion of CaCl₂.Under the same conditions, the monolayer dispersion capacity of dry mixturesamples treated by microwave irradiation is more than one of dry mixture samplestreated by calcination in the system of CaCl₂/10X. The monolayer dispersioncapacity of samples impregnated in aqueous solution treated by microwaveirradiation is more than one of same samples by calcination and it is higher than thetheoretical threshold of CaCl₂/silica gel. The phenomenon needs to be furtherresearched.The ammonia adsorption capacity is 0.31g/g when the adsorption temperature is35℃, 0.08g/g when the adsorption temperature is 85℃and the margin is 0.23g/g forsamples(CaCl₂/10X, 0.5g/g) of dry mixture treated by calcination. The ammoniaadsorption capacity is 0.54g/g when the adsorption temperature is 35℃, 0.07g/gwhen the adsorption temperature is 85℃and the margin is 0.47g/g forsamples(CaCl₂/10X, 0.5g/g) of dry mixture treated by microwave irradiation. Theammonia adsorption capacity is 0.39g/g when the adsorption temperature is 35℃,0.12g/g when the adsorption temperature is 85℃and the margin is 0.27g/g for samples(CaCl₂/silica gel, 0.5g/g) impregnating in aqueous solution treated bycalcination; The ammonia adsorption capacity is 0.62g/g when the adsorptiontemperature is 35℃, 0.15g/g when the adsorption temperature is 85℃and the marginis 0.47g/g for samples(CaCl₂/silica gel, 0.5g/g) impregnating in aqueous solutiontreated by microwave irradiation. The ammonia adsorption capacity of compositeadsorbent is obvious higher than the capacity of 10X zeolite and silica gel, especiallythe composite adsorbent treated by microwave irradiation.It is suggested that the effect of microwave irradiation on the dispersion ofCaCl₂ onto 10X zeolite and silica gel and the reasons for the increase of dispersioncapacity that the sample treated by microwave irradiation should farther be studied inthe more work. The ammonia adsorption capacity of composite adsorbent andpreparation also should farther be studied, especially the effect of differentpreparation conditions on adsorption attenuation.