钛酸锌高温煤气脱硫剂再生行为的研究

The Regenerable Zinc titanate sorbent is one of the leading candidates for hot coal-derived gas desulfurization. The effect of the regeneration temperature, O2 concentration and sorbent granular size on the regeneration reactivity of Zn2TiO4 sorbent were investigated by using the thermogravimetric analyzer. Zinc sulfate formed through side reactions was inferred from TGA curves and was confirmed by the XRD analysis when the sorbent was regenerated at higher concentration of the oxygen and lower temperature(<750℃). The reasonable regeneration conditions should avoid the sulfate formation. Regeneration kinetic studies were also performed at regeneration temperature from 725℃ to 800℃. Higher regeneration temperature and O2 concentration, smaller granular size can increase the regeneration rate. The order of O2 in the reaction can reasonably be assume to be 1. Kinetic model tests show that the regeneration process can be well fitted by the shrinking core model. The kinetic controlling steps transfer with the sorbent conversion. The chemical reaction rate is the controlling step at the early regenerating stage (<65%), while the inner diffusion through the product layer play a dominant role at the latter regenerating stage (>75%). The reaction rate constants and the effective diffusivities were calculated according the model. The apparent activation energy of chemical reaction and corresponding frequency factor are 19.11kJ/mol and 8.01×10－2m/s, respectively. While the diffusion activation energy and corresponding frequency factor are 48.84kJ/mol and 3.12×10－4m2/s, respectively.