Lab-scale investigations on catalyst recovery of gasified residue collected from the potassium-catalyzed steam gasification process

The catalyst recovery process was investigated utilizing different washing methods and operating conditions after potassium-catalyzed steam gasification. During potassium-catalyzed steam gasification, the H2 yield and carbon conversion (XC) could reach 101.18 g/kg-coal and 73.39%, respectively, when utilizing Lanna clean coal as a sample; the potassium compounds mainly existed in three forms: KAlSiO4, KHCO3, and K2SO4. In the catalyst recovery process, the highest recovery efficiency of potassium (ηK) on Lanna raw coal and clean coal gasified residue reached 92.14% after six limewater washings and 93.37% after three limewater washings, respectively. When utilizing the combined washing method for the Lanna clean coal gasified residue, the recovered catalyst showed a longer catalyst reuse lifetime even though the recovery efficiency of potassium (ηK) only reached 89.42%, which was 4% lower than that obtained after three limewater washings.