SAPO分子筛的二甲苯异构化反应性能研究——酸性和孔结构对其催化性能的影响

采用水热法合成了SAPO-5、SAPO1-1、SAPO-41分子筛，并以间二甲苯异构化反应为模型反应，考察了SAPO-5、SAPO-11、SAPO-41的催化性能；运用XRD、BET、吸附吡啶的FT IR等手段表征了SAPO的结构和酸性。结果表明，在合成投料比相同的情况下，SAPO-11具有最大的较强B酸量，表现出了最好的间二甲苯异构催化活性。SAPO-5因为较强B酸中心数目少，异构催化活性最差。三种分子筛的间二甲苯异构化催化活性和较强B酸中心的分布均呈SAPO-5＜SAPO-41≈SAPO-11顺序排列。较强B酸中心的分布是决定催化剂异构化活性的主要因素。中孔分子筛SAPO-11、SAPO-41孔道直径与对位产物的直径接近，对位选择性比大孔分子筛SAPO-5好。     

核磁共振分析技术在重油表征中的研究进展

重油的开发和利用日趋重要。只有对重油的结构和组成有充分的了解,才能合理地利用这部分有限的资源。核磁共振谱图能够直接反映出碳、氢及杂原子所处的化学环境,且分析简便、快捷,从而成为沥青、渣油等重油的结构组成分析的有力工具。本文概述了近年来核磁共振技术在重油结构和组成分析方面所做的主要研究。     

PICARD ITERATION FOR NONSMOOTH EQUATIONS

1. IntroductionConsider the following nonsmooth equationsF(x) = 0 (l)where F: R" - R" is LipsChitz continuous. A lot of work has been done and is bellg doneto deal with (1). It is basicly a genera1ization of the cIassic Newton method [8,10,11,14],Newton-lthe methods[1,18] and quasiNewton methods [6,7]. As it is discussed in [7], the latter,quasiNewton methods, seem to be lindted when aPplied to nonsmooth caJse in that a boundof the deterioration of uPdating matrir can not be maintained w…     

核交联的含磺酸甜菜碱pH敏感胶束的制备与表征

制备了一种在疏水段带有侧基叠氮官能团的两亲性pH敏感的聚合物——聚己内酯-聚(甲基丙烯酸二乙氨基乙酯-磺酸甜菜碱)((PCL-ACL)-PDEAS);同时合成了两端带有炔基中间带有二硫键的交联剂,用红外、核磁表征了目标分子.通过两亲性高分子自组装形成胶束,并通过点击化学反应获得了核交联的胶束.通过动态光散射测定粒径,胶束酸碱滴定表征胶束的pH敏感性,还原条件下释放药物的速度,对比了非交联胶束和交联胶束的性质.结果表明,交联胶束在正常生理条件下的释放速度比未交联胶束更慢;而在有DTT的存在条件下,交联胶束由于二硫键断裂,释放速率明显加快.因此,核交联载药胶束有可能响应肿瘤的微环境实现靶向释放.     

CONVERGENCE OF INEXACT CONIC NEWTON METHODS

A conic Newton method is attractive because it converges to a local minimizzer rapidly from any sufficiently good initial guess. However, it may be expensive to solve the conic Newton equation at each iterate. In this paper we consider an inexact conic Newton method, which solves the couic Newton equation oldy approximately and in sonm unspecified manner. Furthermore, we show that such method is locally convergent and characterizes the order of convergence in terms of the rate of convergence of the relative residuals.     

一阶中立型时滞差分方程振动的充分必要条件

研究了一阶常系数中立型时滞差分方程A[x(n)-px(n-τ)]+qx(n-σ)=0的振动性.通过构造若干适当的函数,分别得到了在01两种情况下该方程的一切解振动的充分必要条件.     

Cu/HMOR催化二甲醚羰基化合成乙酸甲酯: 催化剂制备方法的影响 (cited: 2)

采用氨蒸发法、尿素水解法、离子交换法及浸渍法制备HMOR负载的Cu催化剂, 考察其催化二甲醚(DME)羰基化合成乙酸甲酯(MA)性能. 结果表明离子交换法制得Cu/HMOR催化剂在Cu的金属中心和酸性分子筛载体的共同作用下具有较好催化反应活性. 在210 oC、1.5 MPa、空速4883 h^-1,DME转化率为95.3%,MA选择性为94.9%. 对催化剂进行N2物理吸附、X射线衍射、NH₃程序升温脱附和CO程序升温脱附等表征发现,离子交换法制得Cu/HMOR催化剂具有较高比表面、大量弱酸及一定中强酸、适中的CO吸附强度,提高了CO插入DME羰基化反应活性.     

Urchin-like CoCu Bimetallic Nanocomposites for Catalytic Hydrogenolysis of Glycerol to Propanediols

Bimetallic CoCu nanocomposites were synthesized in polyol by using Ru as heterogeneous nucleation agent and stearic acid as surfactant, and their catalytic properties were investi- gated by hydrogenolysis of glycerol to propanediols. It was found that the surfactant could induce Co nanocrystals to form nanowires as structure-directing agent, while it's ineffective for Cu because only spherical Cu particles were produced under the same condition. When Co²⁺ and Cu²⁺ coexist in polyol, Cu²⁺ is firstly reduced and forms the spherical particles, and then the Cu particles afford surface for the subsequential reduction of Co²⁺ and growth of Co nanocrystals to form the nanorods, obtaining the urchin-like CoCu nanocomposites. The catalytic performance in selective hydrogenolysis of glycerol to propanediols proposed that the CoCu urchin-like nanocomposites was superior to the Co nanowires possibly due to that the synergistic effect between Co and Cu component promoted conversion of glyc-erol and obtained the higher propanediol yields based on the specific surface areas of the catalysts.     

Bio-methanol from Bio-oil Reforming Syngas Using Dual-reactor

A dual-reactor, assembled with the on-line syngas conditioning and methanol synthesis, was successfully applied for high efficient conversion of rich CO₂ bio-oil derived syngas to bio-methanol. In the forepart catalyst bed reactor, the catalytic conversion can effectively adjust the rich-CO₂crude bio-syngas into the CO-containing bio-syngas using the CuZnAlZr catalyst. After the on-line syngas conditioning at 450 oC, the CO₂/CO ratio in the bio-syngas significantly decreased from 6.3 to 1.2. In the rearward catalyst bed reactor, the conversion of the conditioned bio-syngas to bio-methanol shows the maximum yield about 1.21 kg/(kg_catal·h) MeOH with a methanol selectivity of 97.9% at 260 oC and 5.05 MPa using conventional CuZnAl catalyst, which is close to the level typically obtained in the conventional methanol synthesis process using natural gas. The influences of temperature, pressure and space velocity on the bio-methanol synthesis were also investigated in detail.     

Production of Mixed Alcohols from Bio-syngas over Mo-based Catalyst

A series of Mo-based catalysts prepared by sol-gel method using citric acid as complexant were successfully applied in the high effcient production of mixed alcohols from bio-syngas, derived from the biomass gasification. The Cu₁Co₁Fe₁Mo₁Zn_0.5-6%K catalyst exhibited a higher activity on the space-time yield of mixed alcohols, compared with the other Mo-based catalysts. The carbon conversion significantly increases with rising temperature below 340 oC, but the alcohol selectivity has an opposite trend. The maximum mixed alcohols yield derived from biomass gasification is 494.8 g/(kg_catal·h) with the C2⁺ (C2-C6 higher alcohols) alcohols of 80.4% under the tested conditions. The alcohol distributions are con-sistent with the Schulz-Flory plots, except methanol. In the alcohols products, the C2⁺ alcohols (higher alcohols) dominate with a weight ratio of 70%-85%. The Mo-based cata-lysts have been characterized by X-ray diffraction and N2 adsorption/desorption. The clean bio-fules of mixed alcohols derived from bio-syngas with higher octane values could be used as transportation fuels or petrol additives.