The coke deposition on HZSM-5/SAPO-34 composite catalysts has been studied in the conversion of ethanol to propylene. The HZSM-5/SAPO-34 composite catalysts were synthesized by hydrothermal method（ZS-HS） and fully b...The coke deposition on HZSM-5/SAPO-34 composite catalysts has been studied in the conversion of ethanol to propylene. The HZSM-5/SAPO-34 composite catalysts were synthesized by hydrothermal method（ZS-HS） and fully blending（ZS-MM）. The used catalysts were characterized by XRD, N;adsorption–desorption, TGA, TPO, elemental analysis, FTIR and XPS. The coking kinetics on both ZS-HS and ZS-MM has been investigated and their coking rate equations were obtained. The used ZS-MM catalyst had higher amount of coke and lower nC:nHthan the used ZS-HS. 90% of the coke was deposited in the micropores of ZS-HS, while almost 45% of the coke located in the micropores of ZS-MM. The coke deposited on ZS-HS catalyst was mainly graphite-like carbon species, whereas dehydrogenated coke species was the major on ZS-MM. The coking activation energy of ZS-MM was lower than that of ZS-HS, and the coking rate on ZS-MM was faster than on ZS-HS. In addition, the regeneration of ZS-MM catalyst showed that it had a good hydrothermal stability. The differences on coking behaviors on the two catalysts were due to their different acidic properties and textures.展开更多
本文使用机械混合法和浸渍法制备了一系列的氧化锌负载HZSM-5/SAPO-34(HZ-SA)混合载体催化剂,并且首次将其应用于正丁烷芳构化的研究中.在反应条件为T=580?C,P=100KPa,WHSV=1 500 m L·g^(-1)·h^(-1)条件下,在Zn/HZ-SA催化剂上...本文使用机械混合法和浸渍法制备了一系列的氧化锌负载HZSM-5/SAPO-34(HZ-SA)混合载体催化剂,并且首次将其应用于正丁烷芳构化的研究中.在反应条件为T=580?C,P=100KPa,WHSV=1 500 m L·g^(-1)·h^(-1)条件下,在Zn/HZ-SA催化剂上,最高的正丁烷转化率和BTX(苯,甲苯,二甲苯)收率可以分别达到76.5%和26.4%,远高于在Zn/HZSM-5上的49.1%和18.6%,以及Zn/SAPO-34的19.0%和1.1%.由XRD,BET,NH_3-TPD,Py-FIIR等表征结果可知,Zn/HZ-SA催化剂具有相对较大的比表面积和较多的活性位点,以及中等强度和密度的酸性位点,改善了催化剂的催化性能.除此之外,混合载体(HZ-SA)中HZSM-5和SAPO-34之间的协同作用,也可能是Zn/HZ-SA催化剂取得优异催化性能的原因.展开更多
A series of SAPO-34 molecular sieves with different SiO_(2)/Al_(2)O_(3)ratios have been synthesized for the methanol-to-olefin(MTO)reaction.Their physico-chemical properties are characterized by various techniques suc...A series of SAPO-34 molecular sieves with different SiO_(2)/Al_(2)O_(3)ratios have been synthesized for the methanol-to-olefin(MTO)reaction.Their physico-chemical properties are characterized by various techniques such as X-ray diffraction(XRD),scanning electron microscopy(SEM),energy dispersive spectroscopy(EDS),Fourier transform infrared spectroscopy(FT-IR)and N2 adsorption-desorption.The results are compared with those of the commercial HZSM-5,which show that the crystallinity and particle diameter of SAPO-34 as well as HZSM-5 increase with SiO_(2)/Al_(2)O_(3)ratio.The variation of BET surface area of SAPO-34 is different from that of HZSM-5 and the sample with SiO_(2)/Al_(2)O_(3)ratio of 0.4 exhibits the highest BET surface area.FT-IR spectra indicate that HZSM-5 has both Brǿnsted and Lewis acid sites and Brǿnsted acid sites are stronger,whereas SAPO-34 samples are dominated only by Lewis acid sites.When the SiO_(2)/Al_(2)O_(3)ratio increases,propylene and butylenes become the predominant product of the MTO reaction over HZSM-5.In contrast,the main products of this reaction catalyzed by SAPO-34 are ethylene and propylene.According to the product distribution,the reaction mechanism over HZSM-5 catalysts is proposed.展开更多
基金support for this work from National Ministry of Education(No.NCET-10-878)Shaanxi Province(No.2011ZKC4-08,2009ZDKG-70)Northwest University(10YSY08)
文摘The coke deposition on HZSM-5/SAPO-34 composite catalysts has been studied in the conversion of ethanol to propylene. The HZSM-5/SAPO-34 composite catalysts were synthesized by hydrothermal method（ZS-HS） and fully blending（ZS-MM）. The used catalysts were characterized by XRD, N;adsorption–desorption, TGA, TPO, elemental analysis, FTIR and XPS. The coking kinetics on both ZS-HS and ZS-MM has been investigated and their coking rate equations were obtained. The used ZS-MM catalyst had higher amount of coke and lower nC:nHthan the used ZS-HS. 90% of the coke was deposited in the micropores of ZS-HS, while almost 45% of the coke located in the micropores of ZS-MM. The coke deposited on ZS-HS catalyst was mainly graphite-like carbon species, whereas dehydrogenated coke species was the major on ZS-MM. The coking activation energy of ZS-MM was lower than that of ZS-HS, and the coking rate on ZS-MM was faster than on ZS-HS. In addition, the regeneration of ZS-MM catalyst showed that it had a good hydrothermal stability. The differences on coking behaviors on the two catalysts were due to their different acidic properties and textures.
基金Supported by the National Science Foundation of China(21366030)
文摘本文使用机械混合法和浸渍法制备了一系列的氧化锌负载HZSM-5/SAPO-34(HZ-SA)混合载体催化剂,并且首次将其应用于正丁烷芳构化的研究中.在反应条件为T=580?C,P=100KPa,WHSV=1 500 m L·g^(-1)·h^(-1)条件下,在Zn/HZ-SA催化剂上,最高的正丁烷转化率和BTX(苯,甲苯,二甲苯)收率可以分别达到76.5%和26.4%,远高于在Zn/HZSM-5上的49.1%和18.6%,以及Zn/SAPO-34的19.0%和1.1%.由XRD,BET,NH_3-TPD,Py-FIIR等表征结果可知,Zn/HZ-SA催化剂具有相对较大的比表面积和较多的活性位点,以及中等强度和密度的酸性位点,改善了催化剂的催化性能.除此之外,混合载体(HZ-SA)中HZSM-5和SAPO-34之间的协同作用,也可能是Zn/HZ-SA催化剂取得优异催化性能的原因.
基金This research was supported financially by the National High Technology Research and Development Program of China(863 Program)(Grant Nos.2006AA06Z371 and 2008AA06Z324)the Innovation Project of Institute of Process Engineering,Chinese Academy of Sciences(No.082702).
文摘A series of SAPO-34 molecular sieves with different SiO_(2)/Al_(2)O_(3)ratios have been synthesized for the methanol-to-olefin(MTO)reaction.Their physico-chemical properties are characterized by various techniques such as X-ray diffraction(XRD),scanning electron microscopy(SEM),energy dispersive spectroscopy(EDS),Fourier transform infrared spectroscopy(FT-IR)and N2 adsorption-desorption.The results are compared with those of the commercial HZSM-5,which show that the crystallinity and particle diameter of SAPO-34 as well as HZSM-5 increase with SiO_(2)/Al_(2)O_(3)ratio.The variation of BET surface area of SAPO-34 is different from that of HZSM-5 and the sample with SiO_(2)/Al_(2)O_(3)ratio of 0.4 exhibits the highest BET surface area.FT-IR spectra indicate that HZSM-5 has both Brǿnsted and Lewis acid sites and Brǿnsted acid sites are stronger,whereas SAPO-34 samples are dominated only by Lewis acid sites.When the SiO_(2)/Al_(2)O_(3)ratio increases,propylene and butylenes become the predominant product of the MTO reaction over HZSM-5.In contrast,the main products of this reaction catalyzed by SAPO-34 are ethylene and propylene.According to the product distribution,the reaction mechanism over HZSM-5 catalysts is proposed.
