Hydrothermal synthesis of boehmites with various particle sizes and transition to α-Al2O3 powders by calcination

Boehmite powders with various particle sizes have been prepared by hydrothermal method and the α-Al2 O3 powders yielded after subsequent calcination have been studied. Dispersive crystalline boehmite powders of 30-100 nm, 0.4-0. 6μm and 1μm in size were obtained respectively by changing the hydrothermal precursors and the pH value of hydrothermal slurry. Calcination of boehmite powders of 30-100 nm at 1250℃ for 1h resulted in the formation of single-phase α-Al2O3,and the products consisted of vermicular particles. The boehmite powders of 0.4-0.6μm were also fully converted to α-Al2O3 at 1250℃, and the products consisted of plate-like particles with the same size of 0. 4-0. 6μm. The boehmite powders of 1μm calcined at 1350℃ for 2h were still composed of a little proportions of transition aluminas besides α-Al2 O3, and the particles sintered severely. The reaction processes for the formation of crystalline boehmites under hydrothermal conditions and α-Al2O3 powders during calcination have been discussed.     

2,4,6-三甲基苯乙酸的合成新方法

以2,4,6-三甲基苯甲醛为原料,通过相转移催化反应在水-氯仿体系中先合成α-羟基-2,4,6-三甲基苯乙酸(收率52%);再通过次磷酸还原α-羟基-2,4,6-三甲基苯乙酸得到最终产物2,4,6-三甲基苯乙酸(收率91%)。此法绿色便捷,成本相对较低。     

CO偶联合成草酸酯催化剂国内专利技术进展

以煤炭为资源,通过CO气相偶联制备草酸酯、进而加氢合成乙二醇,成为间接法合成乙二醇的最佳工艺路线.在中国,已经利用该工艺建成了多套20× 104t/a级的工业装置,在“十二五”期间,还要陆续建设总产能约400×104t/a的乙二醇装置.中国在煤制乙二醇成套技术的开发和应用上走到了世界前列.CO偶联合成草酸酯催化剂技术,催化剂一般由载体、主催化剂和助催化剂组成.该催化剂的载体主要为α-A12O3,也可以是6-A12O3、SiO2、分子筛或以它们为主构成的复合载体;贵金属Pd几乎成为不可或缺的主催化剂.在此基础上,陆续开发了含一种、两种或三种助催化剂的催化剂体系,助催化剂主要选自La系元素、碱土金属元素、Fe、Cu、Mo、W、Co、Zn及Ti等过渡金属元素.同时,综述了复合载体催化剂、规整催化剂及金属骨架催化剂的进展.在一定的工艺条件下,CO单程转化率几乎接近75％,草酸酯选择性接近100％,草酸酯时空产率在1000g/(L·h).     

Influence of free volume fraction,inter/intramolecular energy ratio,and chain segment density on the Gibbs-DiMarzio theory of the glass transition

Based upon computer analysis, the Gibbs-DiMarzio (G-DM) theory is evaluated for the case of (a) constant V₀ and (b) constant r where V₀ is the fractional free volume at T_g and r is the ratio of the hole (E₀) to the flex (ε) energy. For each respective case, results are presented in a reduced variables format that indicate the extent to which r and V₀ vary at the transition temperature as a function of the reciprocal degree of polymerization (P^?1). To further account for chemical differences that exist among polymers, an index (n) is introduced that ultimately incorporates the effective number average of chain atom segments (x?) per P?. Using these reduced variables plots, the effects of V₀, r, and n are compared with the T_g data for four well-documented polymers. Although the theory adequately describes the PMMA, PS, and PVC data, for PαMS the fit is doubtful. The analysis demonstrates that, in order to maintain V₀ within the range of 0.015–0.045, r must remain within approximately 1.0–1.1. Moreover, under conditions of either constant V₀ or r, other more flexible polymers require that $\text{n?10}$.     

α-氯代脂肪酸水热法中性水解合成α-羟基脂肪酸

开发了一条从天然脂肪酸合成α-羟基脂肪酸(α-HFA)的高产率、低污染且低成本的合成路线,即从天然脂肪酸制备α-氯代脂肪酸(α-CFA),再以α-CFA为原料通过水热法中性水解合成α-HFA。用GC-MS和IR鉴定了产物的结构,ESI-MS表征了产物的相对分子质量(以下简称分子量),纯化后α-HFA纯度达99%(GC)以上。探讨了水热中性水解反应中原料配比、反应加水量、反应温度、反应时间等因素对该水热工艺的影响,结果表明,当n(CaCO3)∶n(α-CFA)=1.05∶1,m(H2O)∶m(α-CFA)=2∶1,C12～C18的α-氯代天然脂肪酸在155℃水热条件下反应4 h后,α-HFA同系物的产率均高达98%～99%。     

竞争性抑制剂对反胶团萃取过程中α胰凝乳蛋白酶活力的稳定作用

研究了竞争性抑制剂苯基硼酸对a胰凝乳蛋白酶反胶团萃取过程的影响及对酶活力的稳定作用. 研究发现,向AOT/isooctane 反胶团中添加一定量的苯基硼酸,萃取率会略有增加,反萃取率则无显著变化. 酶活力的回收率显著提高,酶活力对萃取和反萃时间的耐受性显著增强. 苯基硼酸和a胰凝乳蛋白酶之间的特异性亲和作用是产生这种影响的原因.     

负载型铜在萘的α-硝基化反应中的催化性能

目前工业上合成 α-硝基萘仍然采用传统的混酸硝化法,然而该方法存在区域选择性不高、官能团耐受性差、产生过量酸性废液以及后处理费用高等诸多局限性,导致环境污染以及生产成本的提高,不符合绿色化学的理念。鉴于 α-硝基萘的应用前景,本文通过浸渍-焙烧-还原等步骤设计合成一系列负载型铜催化剂,实现了萘向 α-硝基萘的高效、经济、绿色的催化转化。其中,以ZSM-5等为载体合成的催化剂Cu/ZSM-5催化效果最好,以较高的分离产率（高达95%）和优异的区域选择性[(α-∶β-)>(98∶2)]得到了目标产物α-硝基萘,而且在重复使用4次后依然保持较高的催化活性和结构稳定性。     

Integrative Extraction of Ergosterol, （1→3）-α-D-Glucan and Chitosan from Penicillium chrysogenum Mycelia

Abstract Ergosterol,（1→3）-α-D-glucan and chitosan are important biomaterials. In this research, a process has been developed to integratively extract ergosterol, （1→3）-α-D-glucan, and chitosan from Penicillium chrysongenum mycelium. First the mycelia are pretreated with 0.1mol·L^-1 of NaOH. After recovery by centrifugation the solid portion is made to undergo saponification and deacetylation reactaons by addition of 2mol·L^-1 NaOH and et anol.After reaction, extraction is carried out by addition of petroleum ether, which separates the reaction mixture into two phases. The upper layer of petroleum ether contains extracted ergosterol, and the .bottom layer of NaOH solution contains （1→3）-α-DEglucan; the chitosan is on the mycelia residuum. After isolation, the recovery yield of ergosterol is 0.52% of dry mycelium. That of （1→3）-α-D-glucan is about 8.2%; and chitosan is 5.7% with 86% deacetylation. The compositions have been characterized by 1R, HPLC analyses.     

The electroreduction of alkyl iodides and polyiodides: The kinetic model of EC(C)E and ECE-EC(C)E mechanisms with included transfer coefficient variability

The cyclic voltammetry electroreduction of seven alkyl iodides was investigated in 0.3 M TBAP/DMF on glassy carbon electrode. The influence of carbon chain length and the number of iodine atoms in the molecule was examined. The two-electron reductive cleavage with iodine elimination was numerically resolved into one-electron consecutive steps. The mechanism of the process was discussed applying the mathematical EC(C)E and ECE-EC(C)E kinetic models with included transfer coefficient variability for one stage electroreduction of RI and two stage electroreduction of RI₂, respectively. For electroreduction of diiodomethane the discrimination of elementary alpha parameter between two reduction stages was determined.     

原位添加α晶成核剂对高熔体强度聚丙烯性能的影响

采用过氧化苯甲酰(BPO)为引发剂,通过一步反应挤出法将接枝单体苯乙烯(St)和端乙烯基硅油(VS)接枝到等规聚丙烯(i PP)上制备高熔体强度聚丙烯(HMSPP),同时在制备过程中原位添加α晶成核剂S20或NA11,考察了两种不同的α晶成核剂对HMSPP的制备及其结晶性能、力学性能和发泡性能的影响。熔体流动速率和分子量分布的测试结果表明,S20或NA11的原位添加没有影响i PP接枝反应的进行;差示扫描量热研究表明,成核剂的加入可以有效促进HMSPP的成核结晶,消除了HMSPP结晶过程中的双结晶峰现象,但成核剂的加入对HMSPP的力学性能并无显著影响。S20或NA11的加入可以有效调控发泡样品的泡孔尺寸,使得泡孔直径从38μm增大到50μm以上,发泡倍率也分别从25倍增大到36倍和37倍。