Ⅰ. INTRODUCTIONPhysical treatment of the HZSM-5 catalyst with steam or coking or modification with metal salts produces high para-selectivity catalyst for alkylation or disproportionation of toluene and isomerization...Ⅰ. INTRODUCTIONPhysical treatment of the HZSM-5 catalyst with steam or coking or modification with metal salts produces high para-selectivity catalyst for alkylation or disproportionation of toluene and isomerization of xylene. However, as the para-selectivity increases, the activity always decreases, and vice versa. In this work the effect of展开更多
An enhanced active and selective catalyst consisting of ruthenium supported on dealuminated HY zeolite has been prepared by a wet im- pregnation method. It was found that BET surface area of Ru/HY catalysts significan...An enhanced active and selective catalyst consisting of ruthenium supported on dealuminated HY zeolite has been prepared by a wet im- pregnation method. It was found that BET surface area of Ru/HY catalysts significantly increases after HC1 treatment. This treatment also increases the concentration of strong acid sites in the catalyst. The hydrogenolysis of glycerol over 5 wt% Ru/HY catalyst was investigated at 190-220℃ , an initial H2 pressure of 3-6 MPa, and in 20 wt% glycerol aqueous solution, The results indicate that HC1 treated Ru/HY catalyst shows higher activity compared with the untreated Ru/HY catalyst, and that the glycerol hydrogenolysis efficiency is influenced by the porosity and acidity of the support. A selectivity to 1,2-PDO of 81.3% at a glycerol conversion of 60.1% under 3 MPa H2 pressure and 220 ℃ for 10 h was achieved over the modified Ru/HY catalyst with a 1.0 mol/L HC1 treatment. It has also been shown that a longer reaction time, a higher temperature and a higher H2 pressure have the positive effects on the glycerol hydrogenolysis efficiency of the enhanced Ru/HY.展开更多
The modification of HZSM-5 zeolite with phosphorus and steam has been studied. Results show that 1% phosphorus and steam modified HZSM-5 has the highest catalytic activity for n-heptane. Physicochemical and catalytic ...The modification of HZSM-5 zeolite with phosphorus and steam has been studied. Results show that 1% phosphorus and steam modified HZSM-5 has the highest catalytic activity for n-heptane. Physicochemical and catalytic properties of 1% phosphorus and steam modified HZSM-5 zeolites have been investigated. The X-ray diffraction （XRD） results exhibit that there is considerable variation in the relative intensity of the individual diffraction peaks. The acidity of the samples decreases with an increase in the steaming temperature, which is determined by the IR of adsorbed pyridine and temperature programmed desorption （TPD） of ammonia. The oxidation state of phosphorus shown by XPS is ＋5, and a model for surface structure modification is proposed. The nitrogen adsorption isotherm for all samples is a combination of type I and type IV, all hysteresis loops resemble the H4-type. The density functional and cluster model methods have been invoked to select the phosphorus grafting model, and it was found that the phosphorus grafting model were more probable in the form of the terminal oxygen coordinating with aluminum.展开更多
The variations in structure and acidity on the internal and external surfaces of HY zeolites modified by MgO and SiO2 have been studied by MAS NMR, together with the selective adsorption of perfluorotributyl-amine. 27...The variations in structure and acidity on the internal and external surfaces of HY zeolites modified by MgO and SiO2 have been studied by MAS NMR, together with the selective adsorption of perfluorotributyl-amine. 27AI and 29Si MAS NMR spectra revealed that the modifications led to significant changes of the framework owing to the migration of some non-framework Si and Al into the framework in the course of the modifications. 1H MAS NMR spectra showed that the modifications decreased the acidity of the zeolite surfaces. With an increasing of the loading of the oxides, the acidity of the surface decreased further. Both of the two kinds of Bronsted acidity of the MgO-modified HY zeolites decreased, particularly those in the supercages, while those of the SiO2-modified HY zeolites decreased less, and this result is consistent with that of NH3-TPD. From the adsorption of perfluorotributyl-amine, it was found that the acidic sites on the external surface of the HY zeolite can be completely covered by SiO2展开更多
文摘Ⅰ. INTRODUCTIONPhysical treatment of the HZSM-5 catalyst with steam or coking or modification with metal salts produces high para-selectivity catalyst for alkylation or disproportionation of toluene and isomerization of xylene. However, as the para-selectivity increases, the activity always decreases, and vice versa. In this work the effect of
基金supported by the National Natural Science Foundation of China(21073023 and 21373038)the Fundamental Research Funds for the Central Universities(DUT12YQ03 and DUT13RC(3)41)
文摘An enhanced active and selective catalyst consisting of ruthenium supported on dealuminated HY zeolite has been prepared by a wet im- pregnation method. It was found that BET surface area of Ru/HY catalysts significantly increases after HC1 treatment. This treatment also increases the concentration of strong acid sites in the catalyst. The hydrogenolysis of glycerol over 5 wt% Ru/HY catalyst was investigated at 190-220℃ , an initial H2 pressure of 3-6 MPa, and in 20 wt% glycerol aqueous solution, The results indicate that HC1 treated Ru/HY catalyst shows higher activity compared with the untreated Ru/HY catalyst, and that the glycerol hydrogenolysis efficiency is influenced by the porosity and acidity of the support. A selectivity to 1,2-PDO of 81.3% at a glycerol conversion of 60.1% under 3 MPa H2 pressure and 220 ℃ for 10 h was achieved over the modified Ru/HY catalyst with a 1.0 mol/L HC1 treatment. It has also been shown that a longer reaction time, a higher temperature and a higher H2 pressure have the positive effects on the glycerol hydrogenolysis efficiency of the enhanced Ru/HY.
文摘The modification of HZSM-5 zeolite with phosphorus and steam has been studied. Results show that 1% phosphorus and steam modified HZSM-5 has the highest catalytic activity for n-heptane. Physicochemical and catalytic properties of 1% phosphorus and steam modified HZSM-5 zeolites have been investigated. The X-ray diffraction （XRD） results exhibit that there is considerable variation in the relative intensity of the individual diffraction peaks. The acidity of the samples decreases with an increase in the steaming temperature, which is determined by the IR of adsorbed pyridine and temperature programmed desorption （TPD） of ammonia. The oxidation state of phosphorus shown by XPS is ＋5, and a model for surface structure modification is proposed. The nitrogen adsorption isotherm for all samples is a combination of type I and type IV, all hysteresis loops resemble the H4-type. The density functional and cluster model methods have been invoked to select the phosphorus grafting model, and it was found that the phosphorus grafting model were more probable in the form of the terminal oxygen coordinating with aluminum.
文摘The variations in structure and acidity on the internal and external surfaces of HY zeolites modified by MgO and SiO2 have been studied by MAS NMR, together with the selective adsorption of perfluorotributyl-amine. 27AI and 29Si MAS NMR spectra revealed that the modifications led to significant changes of the framework owing to the migration of some non-framework Si and Al into the framework in the course of the modifications. 1H MAS NMR spectra showed that the modifications decreased the acidity of the zeolite surfaces. With an increasing of the loading of the oxides, the acidity of the surface decreased further. Both of the two kinds of Bronsted acidity of the MgO-modified HY zeolites decreased, particularly those in the supercages, while those of the SiO2-modified HY zeolites decreased less, and this result is consistent with that of NH3-TPD. From the adsorption of perfluorotributyl-amine, it was found that the acidic sites on the external surface of the HY zeolite can be completely covered by SiO2
基金supported by the National Natural Science Foundation of China(21276184,U1332102,21476160)the Specialized Research Fund for the Doctoral Program of Higher Education of China(20120032110014)+1 种基金the Natural Science Foundation of Tianjin(12JCYBJC14000,15JCZDJC37400)the Program for Introducing Talents of Discipline to Universities of China(B06006)~~
