反应详情

FIG. 1 depicts the cycle (a) in which hydrogen is the product and sodium is the alkali metal, and in which sodium carbonate is used in step 2. In the first step cerium oxide is reacted in the solid phase with dibasic sodium phosphate at about 750°-950° C. to provide sodium cerous phosphate, sodium phosphate, oxygen and water. The oxygen is recovered from the gaseous phase and the water removed from the reaction zone. The solid phase is conducted to reaction 2 wherein it is contacted with water and stream and sodium carbonate at 650°-950° C. The reaction produces ceric oxide plus sodium phosphate, carbon dioxide, and hydrogen. The hydrogen can be recovered separately as shown or can be passed directly to step 3 as hereinbefore described. In step 3 the cerium oxide and hydrogen do not participate in the reaction, wherein sodium phosphate is reacted with water and carbon dioxide to produce dibasic sodium phosphate and sodium bicarbonate. The preferred CO2 pressure for this step is about 1 atmosphere. It is preferred that the cerium oxide and sodium phosphate be contacted with carbon dioxide in the presence of only enough water to dissolve most of the sodium bicarbonate produced so that a solid mixture of cerium oxide dibasic sodium phosphate can be recycled directly to step 1 and only a small amount of water need be evaporated to recover the bicarbonate.