The Al2O3-supported PtAg catalysts were prepared and evaluated for the dehydrogenation of n-butane at 550°C in the presence of H2. The PtAg/Al2O3 catalyst prepared by an impregnation method using the Cl- removing...The Al2O3-supported PtAg catalysts were prepared and evaluated for the dehydrogenation of n-butane at 550°C in the presence of H2. The PtAg/Al2O3 catalyst prepared by an impregnation method using the Cl- removing Pt/Al2O3 and AgNO3 showed a higher activity and selectivity to butenes and 1,3-butadiene compared to the Pt/Al2O3 catalyst, but a large amount of coke (about 30 wt% versus the catalyst weight) was formed during the dehydrogenation. The free Ag metal on the prepared catalyst dramatically promoted the coke formation, because the dehydrogenation of 1-butene over the Ag/Al2O3 catalyst produced a large amount of coke. The Cl- addition to the Cl- free Pt/Al2O3 catalyst decreased the coke formation by the reaction of the free Ag particles and Cl to form AgCl which was inactive for the coke formation. The highest initial conversion (50.3%) was obtained with the selectivity to butenes and 1,3-butadiene (butenes = 80.2% and 1,3-butadiene = 5.9%) when the PtAg/Al2O3 catalyst modified with Cl- was used.展开更多
Effect of reaction temperature and pressure on the metathesis reaction between ethene and 2-butene to propene was studied on the WO3/γ-Al2O3-HY catalyst. The activity is found to increase with elevated temperature an...Effect of reaction temperature and pressure on the metathesis reaction between ethene and 2-butene to propene was studied on the WO3/γ-Al2O3-HY catalyst. The activity is found to increase with elevated temperature and reaches a plateau at 150-240 ℃. After that, the activity undergoes a remarkable decrement at too high temperature. The effect of temperature is elucidated by the oxidation state of tungsten species. The evaluation results also indicate that the stability is dependent on this reaction parameter. Medium pressure （0.5-0.8 MPa） is favorable for stability, while atmospheric pressure or too high pressure （〉1.0 MPa） deteriorates the stability. For explanation, UV Vis, FT-IR, O2-TPO, and TG techniques are used to characterize the spent catalysts.展开更多
文摘The Al2O3-supported PtAg catalysts were prepared and evaluated for the dehydrogenation of n-butane at 550°C in the presence of H2. The PtAg/Al2O3 catalyst prepared by an impregnation method using the Cl- removing Pt/Al2O3 and AgNO3 showed a higher activity and selectivity to butenes and 1,3-butadiene compared to the Pt/Al2O3 catalyst, but a large amount of coke (about 30 wt% versus the catalyst weight) was formed during the dehydrogenation. The free Ag metal on the prepared catalyst dramatically promoted the coke formation, because the dehydrogenation of 1-butene over the Ag/Al2O3 catalyst produced a large amount of coke. The Cl- addition to the Cl- free Pt/Al2O3 catalyst decreased the coke formation by the reaction of the free Ag particles and Cl to form AgCl which was inactive for the coke formation. The highest initial conversion (50.3%) was obtained with the selectivity to butenes and 1,3-butadiene (butenes = 80.2% and 1,3-butadiene = 5.9%) when the PtAg/Al2O3 catalyst modified with Cl- was used.
基金Financial support by National Natural Science Foundation of China (No. 20303019)National 973 Project of China (No.2003CB615802).
文摘Effect of reaction temperature and pressure on the metathesis reaction between ethene and 2-butene to propene was studied on the WO3/γ-Al2O3-HY catalyst. The activity is found to increase with elevated temperature and reaches a plateau at 150-240 ℃. After that, the activity undergoes a remarkable decrement at too high temperature. The effect of temperature is elucidated by the oxidation state of tungsten species. The evaluation results also indicate that the stability is dependent on this reaction parameter. Medium pressure （0.5-0.8 MPa） is favorable for stability, while atmospheric pressure or too high pressure （〉1.0 MPa） deteriorates the stability. For explanation, UV Vis, FT-IR, O2-TPO, and TG techniques are used to characterize the spent catalysts.
