title: Oil removal of spent hydrotreating catalyst CoMo/Al2O3 via a facile method with enhanced metal recovery.
abstract: Deoiling process is a key issue for recovering metal values from spent hydrotreating catalysts. The oils can be removed with organic solvents, but the industrialized application of this method is greatly hampered by the high cost and complex processes. Despite the roasting method is simple and low-cost, it generates hardest-to-recycle impurities (CoMoO4 or NiMoO4) and enormous toxic gases. In this study, a novel and facile approach to remove oils from the spent hydrotreating catalysts is developed. Firstly, surface properties of spent catalysts are characterized to reveal the possibility of oil removal. And then, oils are removed with water solution under the conditions of 90°C, 0.1wt% SDS, 2.0wt% NaOH and 10ml/gL/S ratio for 4h. Finally, thermal treatment and leaching tests are carried out to further explore the advantages of oil removal. The results show that no hardest-to-recycle impurity CoMoO4 is found in XPS spectra of thermally treated samples after deoiling and molybdenum is leached completely with sodium carbonate solution. It means that the proposed deoiling method can not only remove oils simply and without enormous harmful gases generating, but also avoid the generation of detrimental impurity and promote recycling of valuable metals from spent hydrotreating catalysts.
authors.affiliation: Institute of Nuclear and New Energy Technology, Tsinghua University, Beijing 100084, China.
authors.forename: Yue
authors.initials: Y
authors.lastname: Yang
authors.affiliation: Institute of Nuclear and New Energy Technology, Tsinghua University, Beijing 100084, China; Beijing Key Lab of Radioactive Wastes Treatment, Tsinghua University, Beijing 100084, China. Electronic address: smxu@tsinghua.edu.cn.
authors.forename: Shengming
authors.initials: S
authors.lastname: Xu
authors.affiliation: Institute of Nuclear and New Energy Technology, Tsinghua University, Beijing 100084, China.
authors.forename: Zhen
authors.initials: Z
authors.lastname: Li
authors.affiliation: Institute of Nuclear and New Energy Technology, Tsinghua University, Beijing 100084, China; Beijing Key Lab of Radioactive Wastes Treatment, Tsinghua University, Beijing 100084, China.
authors.forename: Jianlong
authors.initials: J
authors.lastname: Wang
authors.affiliation: School of Metallurgy and Environment, Central South University, Changsha 410083, Hunan, China.
authors.forename: Zhongwei
authors.initials: Z
authors.lastname: Zhao
authors.affiliation: Institute of Nuclear and New Energy Technology, Tsinghua University, Beijing 100084, China; Department of Chemical and Material Engineering, University of Alberta, Edmonton, Alberta T6G 1H9, Canada. Electronic address: zhenghe.xu@ualberta.ca.
authors.forename: Zhenghe
authors.initials: Z
authors.lastname: Xu
keywords: Oil removal; Selective leaching; Spent catalyst CoMo/Al(2)O(3); Surfactant; Thermal treatment