Shape selective alkylation of polynuclear aromatics has begun to receive increasing attention. 2,6 dialkylnaphthalenes are important raw materials for manufacturing high quality polyester fibers and plastics. Understa...Shape selective alkylation of polynuclear aromatics has begun to receive increasing attention. 2,6 dialkylnaphthalenes are important raw materials for manufacturing high quality polyester fibers and plastics. Understanding of the reaction and the catalysis for conversion of polycyclic aromatic hydrocarbons is needed both from fundamental and practical view points. In this paper, alkylation of naphthalene with propene over a series of dealuminated mordenite with different Si/Al ratios was carried out in an autoclave with an electromagnetical stirrer. Textural property of the dealuminated mordenite was determined by nitrogen adsorption. The amount of the acid sites was measured by NH 3 TPD. The catalytic activity of HM and β shape selectivity for products increased with increasing the Si/Al ratio in HM. Moreover, the selectivity for alkylation with propene was also increased by dealumination treatment. The increase of the catalytic activity was attributed to the formation of mesopores, which significantly promoted the diffusion of reactants and products in mordenite. It was suggested that the increase of β selectivity resulted from the elimination of acid sites from the external surface, and the selectivity for alkylation with propene was improved owing to the creation of the interconnection between 12 ring and 8 rimg channels by dealumination.展开更多
The acetalization and ketalization of various aldehydes and ketones with alcohols by using dealuminated USY(ultrastable Y-type zeolite) as catalyst were studied. The influences of silica/alumina ratio in the catalyst,...The acetalization and ketalization of various aldehydes and ketones with alcohols by using dealuminated USY(ultrastable Y-type zeolite) as catalyst were studied. The influences of silica/alumina ratio in the catalyst, catalyst amount and reaction time on the reaction were investigated. It is showed that the dealuminated USY is a high active catalyst for acetalization and ketaliz ation and its high activity can be readily returned to original by heating at 500 ℃ for 5 hours.展开更多
运用^(29)Si、^(27)Al MAS NMR法研究了氟化物法、络合剂法、水热处理法和酸处理法制备的高硅铝比Y沸石。^(27)Al谱表明,在有络合剂存在下的液固相脱铝产物中不含有非骨架的六配位Al原子。高温水热处理的NH_4Y沸石和抽A1补Si的Y沸石中...运用^(29)Si、^(27)Al MAS NMR法研究了氟化物法、络合剂法、水热处理法和酸处理法制备的高硅铝比Y沸石。^(27)Al谱表明,在有络合剂存在下的液固相脱铝产物中不含有非骨架的六配位Al原子。高温水热处理的NH_4Y沸石和抽A1补Si的Y沸石中除含有四、六配位Al原子外,还含有另一种状态的非骨架Al原子。^(29)QSi谱表明,(NH_4)_2SiF_6法制备的Y沸石中非骨架成分的含量与制备条件有关。该成分的含量可通过对^(29)Si MAS NMR谱图的模拟进行定量估算。展开更多
用^(29)Si MAS NMR、^(27)Al MAS NMR、XRD及IR等方法对4种不同脱铝方法处理的USY、SSY、US-SSY和DAY的微观结构进行了研究,结合脱铝方法讨论了骨架硅铝的分布以及非骨架硅铝和羟基空穴等的形成和含量不同的原因.发现不同脱铝方法可导...用^(29)Si MAS NMR、^(27)Al MAS NMR、XRD及IR等方法对4种不同脱铝方法处理的USY、SSY、US-SSY和DAY的微观结构进行了研究,结合脱铝方法讨论了骨架硅铝的分布以及非骨架硅铝和羟基空穴等的形成和含量不同的原因.发现不同脱铝方法可导致骨架上不同Si(nAl)单元的脱除.XRD结果表明,SSY经进一步高温水蒸汽处理得到的US-SSY的相对结晶度可高达97％.脱铝后,微孔保留愈多,二次孔越少,相对结晶度愈高.最后对^(29)Si MAS NMR、XRD和IR3种测定骨架单胞铝(N_(Al))_F的结果进行了比较.展开更多
The effective B acid amount of dealuminated USY(DUSY) zeolites with different silica/alumina ratios were measured by UV spectrometry with 2,6 dimethyl pyridine as adsorbentes in the presence of cyclohexane or anhydrou...The effective B acid amount of dealuminated USY(DUSY) zeolites with different silica/alumina ratios were measured by UV spectrometry with 2,6 dimethyl pyridine as adsorbentes in the presence of cyclohexane or anhydrous ethanol or tetrahydrofuran.The isomerization of α pinene was used to check the acidic catalytic properties of these zeolites.The results indicate that effective B acid amount of DUSY measured in polar anhydrous ethanol or tetrahydrofuran is lower than that of non polar cyclohexane.The effect of solution concentration of effective B acid amount of DUSY zeolites is small.As the silica/alumina ratio of catalyst increases,effective B acid amount and conversion of isomerization of α pinene all raise.展开更多
文摘Shape selective alkylation of polynuclear aromatics has begun to receive increasing attention. 2,6 dialkylnaphthalenes are important raw materials for manufacturing high quality polyester fibers and plastics. Understanding of the reaction and the catalysis for conversion of polycyclic aromatic hydrocarbons is needed both from fundamental and practical view points. In this paper, alkylation of naphthalene with propene over a series of dealuminated mordenite with different Si/Al ratios was carried out in an autoclave with an electromagnetical stirrer. Textural property of the dealuminated mordenite was determined by nitrogen adsorption. The amount of the acid sites was measured by NH 3 TPD. The catalytic activity of HM and β shape selectivity for products increased with increasing the Si/Al ratio in HM. Moreover, the selectivity for alkylation with propene was also increased by dealumination treatment. The increase of the catalytic activity was attributed to the formation of mesopores, which significantly promoted the diffusion of reactants and products in mordenite. It was suggested that the increase of β selectivity resulted from the elimination of acid sites from the external surface, and the selectivity for alkylation with propene was improved owing to the creation of the interconnection between 12 ring and 8 rimg channels by dealumination.
文摘The acetalization and ketalization of various aldehydes and ketones with alcohols by using dealuminated USY(ultrastable Y-type zeolite) as catalyst were studied. The influences of silica/alumina ratio in the catalyst, catalyst amount and reaction time on the reaction were investigated. It is showed that the dealuminated USY is a high active catalyst for acetalization and ketaliz ation and its high activity can be readily returned to original by heating at 500 ℃ for 5 hours.
文摘运用^(29)Si、^(27)Al MAS NMR法研究了氟化物法、络合剂法、水热处理法和酸处理法制备的高硅铝比Y沸石。^(27)Al谱表明,在有络合剂存在下的液固相脱铝产物中不含有非骨架的六配位Al原子。高温水热处理的NH_4Y沸石和抽A1补Si的Y沸石中除含有四、六配位Al原子外,还含有另一种状态的非骨架Al原子。^(29)QSi谱表明,(NH_4)_2SiF_6法制备的Y沸石中非骨架成分的含量与制备条件有关。该成分的含量可通过对^(29)Si MAS NMR谱图的模拟进行定量估算。
文摘用^(29)Si MAS NMR、^(27)Al MAS NMR、XRD及IR等方法对4种不同脱铝方法处理的USY、SSY、US-SSY和DAY的微观结构进行了研究,结合脱铝方法讨论了骨架硅铝的分布以及非骨架硅铝和羟基空穴等的形成和含量不同的原因.发现不同脱铝方法可导致骨架上不同Si(nAl)单元的脱除.XRD结果表明,SSY经进一步高温水蒸汽处理得到的US-SSY的相对结晶度可高达97％.脱铝后,微孔保留愈多,二次孔越少,相对结晶度愈高.最后对^(29)Si MAS NMR、XRD和IR3种测定骨架单胞铝(N_(Al))_F的结果进行了比较.
文摘The effective B acid amount of dealuminated USY(DUSY) zeolites with different silica/alumina ratios were measured by UV spectrometry with 2,6 dimethyl pyridine as adsorbentes in the presence of cyclohexane or anhydrous ethanol or tetrahydrofuran.The isomerization of α pinene was used to check the acidic catalytic properties of these zeolites.The results indicate that effective B acid amount of DUSY measured in polar anhydrous ethanol or tetrahydrofuran is lower than that of non polar cyclohexane.The effect of solution concentration of effective B acid amount of DUSY zeolites is small.As the silica/alumina ratio of catalyst increases,effective B acid amount and conversion of isomerization of α pinene all raise.
