In order to minimize coke yield during biomass catalytic fast pyrolysis (CFP) process, ethylene diamine tetraacetie acid (EDTA) chemical modification method is carried out to selectively remove the external framework aluminum of HZSM-5 catalyst. X-ray diffraction (XRD), nitrogen (N2)-adsorption and ammonia-temperature programmed desorption (NH3-TPD) techniques are employed to investigate the porosity and acidity characteristics of original and modified HZSM-5 samples. Py-GC/MS and thermo-gravimetric analyzer (TGA) experiments are further conducted to explore the catalytic effect of modified HZSM-5 samples on biomass CFP and to verify the positive effect on coke reduction. Results show that EDTA treatment does not damage the crystal structure of HZSM-5 zeolites, but leads to a slight increase of pore volume and pore size. Meanwhile, the elimination of the strong acid peak indicates the dealumination of outer surface of HZSM-5 zeolites. Treatment time of 2 h (labeled EDTA-2H) is optimal for acid removal and hydrocarbon formation. Among all modified catalysts, EDTA-2H performs the best for deacidification and can obviously increase the yields of positive chemical compositions in pyrolysis products. Besides, EDTA modification can improve the anti-coking properties of HZSM-5 zeolites, and EDTA-2H gives rise to the lowest coke yield.
Bibliographical noteFunding Information:
The authors are grateful for the financial support from the National Basic Research Program of China (973 Program) ( 2013CB228106 ), the National Natural Science Fund Program of China ( 51276040 ), the Scientific Research Foundation of Graduate School of Southeast University ( YBJJ1430 ), the Fundamental Research Funds for the Central Universities and The Scientific Innovation Research Program of College Graduate in Jiangsu Province ( KYLX_0183 ), China Scholarship Council (CSC) , as well as Minnesota Environment and Natural Resources Trust Fund, North Central Regional Sun Grant Center at South Dakota State University through a grant provided by the US Department of Agriculture ( 2013-38502-21424 ) and a grant provided by the US Department of Transportation, Office of the Secretary ( DTOS59-07-G-00054 ).
- Chemical modification
- Ethylene diamine tetraacetie acid
- External framework aluminum