关键词: 水煤气变换反应, 自催化, 氯化钙, 水合物, 一氧化碳

Abstract:

Under the urgent need to reduce the energy consumption of industrial thermal dehydration processes, this work reports a new strategy for low-energy dehydration of hydrated calcium chloride coupled with low-temperature water-gas shift (WGS) reaction based on the basic principle of reaction coupling. Using industrial-garde hydrated calcium chloride as raw material, water with certain chemical reactivity in hydrated calcium chloride was directly used as a reactant in the water-gas shift reaction. The experimental results showed that the residual crystallized water number was reduced to 0.38 via this coupling process at 413 K for 2 h, while there is 0.37 via the tradition way at 413 K for 3 h. In this way, a type Ⅰ industrial anhydrous calcium chloride product (CaCl₂·0.38H₂O) was prepared by coupling catalytic dehydration with the treatment time shortened by 1/3, indicating that the coupled catalytic dehydration strategy is conducive to saving energy consumption. In situ FTIR and CO-TPD-MS experiments showed that CO can be chemically or quasi-chemically adsorbed on the surface of hydrated calcium chloride samples, and MS analysis detected CO₂ and H₂ in the dehydration products, indicating that coupled catalytic dehydration indeed occurred. Furthermore, SEM, BET and MIP showed that the anhydrous CaCl₂ prepared by coupling WGS reaction dehydration has abundant pore structures, which are formed during coupling WGS reaction dehydration from the surface. The results of the water vapor adsorption test showed that the pore structure is beneficial to increasing the contact area with water, so that it showed a faster water absorption rate than commercial anhydrous calcium chloride. The low-energy consuming coupled catalytic dehydration strategy reported in this work is expected to show universality for the dehydration of more materials.

Key words: water-gas shift reaction, autocatalysis, calcium chloride, hydrate, carbon monoxide