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Zheng, Shourong; Heydenrych, Hilton R.; Röger, H.P.; Jentys, Andreas; Lercher, Johannes A.

doi:10.1023/a:1021476014917

Cited by 79 publications

(44 citation statements)

References 16 publications

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“…Few studies have been done to elucidate the intrinsic nature of supported antimony oxides [14]. It was found that Sb 2 O 3 can be spontaneously dispersed on ZSM-5 in the calcination of the mixture of Sb 2 O 3 and ZSM-5 [18,19]. It was also found that Sb 2 O 3 was easily spread on TiO 2 by heating at elevated temperatures and that the spread Sb 2 O 3 species could be oxidized to Sb 6 O 13 [20].…”

Section: Introductionmentioning

confidence: 99%

Studies on the SbOx species of SbOx/SiO2 catalysts for methane-selective oxidation to formaldehyde

Zhang

Sun

Feng

et al. 2006

Applied Catalysis A: General

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Section: Introductionmentioning

confidence: 99%

Studies on the SbOx species of SbOx/SiO2 catalysts for methane-selective oxidation to formaldehyde

Zhang

Sun

Feng

et al. 2006

Applied Catalysis A: General

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“…This indicates that the conversion of m-xylene to p-xylene is the easiest. The ratio of diffusion coefficients over HZSM-5 between p-,o-, and m-xylene was reported as D P =100D O = 1000D M [11], and as D P =1000D O = 1000D M [43], it is expected that P/O > 1. This means that the amount of p-xylene produced should exceed that of oxylene because o-xylene might undergo further reaction before leaving the zeolite crystal [44].…”

Section: Modeling Resultsmentioning

confidence: 99%

Enhancing p -xylene selectivity during m -xylene transformation using mildly pre-coked ZSM-5 catalyst

Al-Khattaf

2007

Chemical Engineering and Processing - Process Intensification

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In the present work, the transformation of m-xylene was studied over fresh and pre-coked H-ZSM-5 catalyst in a riser simulator over the temperature range of 350-500 o C.Significant differences were observed in both the activity and product selectivity pattern for the two forms of the catalyst.While, the fresh catalyst generally gave higher m-xylene conversion, the pre-coked catalyst produced higher Isomerization/Disproportionation (I/D) and Para/ Ortho xylene (P/O) ratios .For both forms of the catalyst, m-xylene conversion was found to increase with both reaction temperature and reaction time (0-15 s). A maximum conversion of 30.8% was achieved at 500 o C for a reaction time of 15 s using the fresh catalyst. The corresponding value for the pre-coked catalyst was 24.6%. P/O and I/D ratios as high as 2.5 and 10 respectively were observed with the pre-coked catalyst. It was also observed that the P/O and I/D ratios decreased with increasing temperature for both catalyst and that the difference between these ratios for the two catalysts is more pronounced between 400 and 450 o C than at higher temperatures. Kinetic modeling of the m-xylene transformation over the pre-coked catalyst yielded a lower activation energy for p-xylene formation compared to the fresh catalyst. And an activation energy of 17.5 kcal/mol for the of m-xylene dispropotionation was obtained for the precoked catalyst compared to 7.82 kcal/mol for the fresh catalyst. These values are indicative of the restriction posed on disproportionation by the pre-coked catalyst as reflected by higher I/D ratios.

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“…Their results indicate that the surface barriers are related to direct to the entrance into the pores and that the extent of modification can induce discretely enhanced barriers, if larger organic modifying agents are used. While this may be the best-defined example, a plethora of methods is reported in the literature [84][85][86][87]. These attempts indicate that an exact control of the pore dimensions, of the surface morphology, as well as of the distribution of the acidic sites will allow rational design of catalysts and sorbents [10,22,32].…”

Section: Introductionmentioning

confidence: 99%