Entropy of Zeolitic Water

Zeolite-water heat-pump system is suitable for effective use of low temperature heat sources such as solar energy and waste heats from factories, that is,for energy saving. The heat exchange function of zeolite owes obviously to the nature of the zeolitic water, the state of which can be described in terms of the entropy value as an independent component of H₂O. Most entropy values of zeolitic water have been given so far to be intermediate between those of liquid water (69.9 J mol^-1 K^-1 at 298 K) and ice (41.5 J mol^-1 K^-1 at 273 K).The present calorimetric measurements proved, however, that the entropy value for Mg-exchanged A-type zeolite is so small, even at the ambient temperature, as to be compared with the residual entropy of ice at 0 K. This revised version was published online in July 2006 with corrections to the Cover Date.     

Adsorption Equilibrium and Dynamics of Methyl Iodide in a Silver Ion-Exchanged Zeolite Column at High Temperatures

An extensive evaluation was carried out to determine the optimal silver ion-exchanged level for the removal of methyl iodide at high temperatures up to 400°C. Based on the degree of silver utilization, the optimal silver loading and temperature were about 10 wt% and 175°C, respectively. The physical and chemical properties of silver ion-exchanged zeolite were characterized by instrumental analysis such as BET, TG/DTA and SEM-EDS. Adsorption dynamics was also studied at different temperatures, and methyl iodide concentrations. A simple dynamic model was formulated by employing the linear driving force (LDF) approximation inside adsorbent particles, and the nonisothermal Langmuir-Freundlich equation. The model equations were solved numerically by an orthogonal collocation method. The proposed dynamic model satisfactorily simulated the experimental breakthrough results.     

超微NaY分子筛的合成(Ⅱ)——添加铝络合剂的影响

NaY分子筛合成体系中添加铝的络合剂(乙二胺四乙酸、柠檬酸和醋酸),可有效地减小分子筛的晶粒尺寸及增加分子筛的晶化速度和SiO2/Al2Oa物质的量比.在添加柠檬酸的合成体系中,考察了柠檬酸的添加量对NaY分子筛晶化行为的影响.发现存在着一个最佳的柠檬酸的添加量范围,即n(柠檬酸)：n(氧化铝)≤2：1,在此范围内,NaY的晶化速率和硅铝比较高,而晶粒尺寸较小.     

HZSM-5沸石分子筛上苯酚与甲醇的烷基化反应

 在n（PhOH）／n（CH3OH）＝1,WGSV＝0．5h－1,T＝673K的反应条件下,研究了HZSM－5,HZSM－23和改性HZSM－5分子筛上苯酚与甲醇烷基化反应的规律．结果表明,分子筛外表面的酸中心对苯酚烷基化反应的贡献较大．用4－甲基喹啉使分子筛外表面的酸中心中毒后,影响反应产物选择性的主要因素是分子筛的孔径．孔径较小的HZSM－23分子筛对提高芳香醚的选择性,抑制二甲酚的生成和提高对甲酚的选择性有利．间甲酚和二甲酚可以在HZSM－5沸石的孔道内生成,但在HZSM－23的孔道内受到抑制．用P2O5,MgO和Sb2O3对HZSM－5改性都可以提高芳香醚的选择性,降低甲酚和二甲酚的选择性．随着氧化物负载量的增加,邻甲酚选择性升高．适度的氧化物改性可以提高对甲酚的选择性,改性效果为Sb2O3＞P2O5＞MgO．     

不同方法制备的Mo/HZSM-5催化剂上甲烷的芳构化反应

 采用机械混合、机械混合后焙烧和机械混合后微波处理等方法制备Mo／HZSM－5催化剂,并对催化剂上甲烷芳构化反应性能进行了考察．结果表明,与浸渍法相比,用机械混合法、固相反应法和微波法制备的催化剂,在保持甲烷转化率不变的前提下,能明显提高芳烃选择性并减少积炭的生成;不同方法制备的Mo／HZSM－5催化剂上Mo物种的落位不同,机械混合法、固相反应法和微波法使Mo物种较多地落位于分子筛外表面．结合反应结果可以得出,落位于分子筛外表面的Mo物种对甲烷芳构化反应更为有利,而且明显减少积炭的生成．     

含碱金属离子分子筛的添加对FCC催化剂催化性能的影响

 通过添加含碱金属离子的分子筛,提高了流化床催化裂化（FCC）催化剂的氢转移反应活性和重油转化能力,同时保持了较低的焦炭选择性．着重考察了碱金属离子和分子筛的类型以及分子筛的硅铝比和晶粒度对催化剂性能的影响规律．结合分子筛及催化剂的酸碱性质及氢吸附与脱附性能的测试结果,初步探讨了含碱金属离子的分子筛的作用机理．     

CuNaY分子筛上汽油馏分中含硫组分的选择吸附及其红外光谱研究

本文从基础研究的角度出发,以红外光谱技术为主要研究手段,以噻吩为汽油馏分中含硫有机分子的模型化合物,首次给出了噻吩分子在吸附剂表面的吸附方式和吸附位,以及芳烃对噻吩吸附的影响等红外光谱信息.为避免吸附剂的强酸性可能引起的干扰,采用NaY分子筛为原料进行液相离子交换制备吸附剂.     

SOLID STATE SYNTHESIS OF SUBSTITUTED COUMARIN-3-CARBOXYLIC ACIDS VIA THE KNOEVENAGEL CONDENSATION UNDER MICROWAVE IRRADIATION

Synthesis of substituted coumarin-3-carboxylic acids using the Knovenagel reaction of malonic acid and O-hydroxyaryl aldehydes supported onto HZSM-5 zeolite under microwave irradiation is described.