The Use of Lewis Acids During Rapid Steam Hydrolysis

Mixed hardwood chips were treated with various concentrations of aluminum chloride hexahydrate, aluminum sulfate hydrate, and ferric chloride and were subjected to rapid steam hydrolysis pretreatment (RASH). The three levels included 0.01, 0.03, and 0.05 moles of catalyst per 1000 grams of wood. Rapid steam hydrolysis (RASH) was done from 180° to 260°C at 20°C intervals for one minute. The Lewis acid catalyst affected the overall recovery yield of solids, the recovery values of the individual components, the enzymatic rates, and the methanol and water solubility. Overall recovery of pretreated solids generally decreased with the increase in levels of the catalyst. The one exception was AlCl₃ ·6H₂O where the minimum recovery levels were reached at 0.03 moles per 1000 grams of wood and increased at the higher level of catalyst. Cellulose degradation occurred in the temperature range of 250° to 260°C for the control and at the two lower concentrations of the catalyst. At the higher levels of catalyst, appreciable amounts of cellulose degradation occurred at lower temperatures. Hemicellulose solubilization and degradation were extremely sensitive to the RASH temperature and to the levels of catalyst. Almost all hemicellulose was lost at high temperatures or at high levels of catalyst. Losses of lignin appeared to be affected mainly by the RASH temperature and not by the changes in the levels of catalyst.

In contrast, both the temperature and the level of catalyst strongly affected the rates of enzymatic hydrolysis. Generally, the intermediate level of catalyst seemed to give the highest rates of enzymatic hydrolysis at the lowest temperature. Methanol and water solubles increased in the presence of the catalyst and reached a maximum at levels of 0.03 moles between 230° to 250°C.     

TiO2悬浮体系下光催化降解愈创木酚的动力学研究

以木素的模型物愈创木酚(G-M)为对象,采用自制的纳米TiO_2作光催化剂,对G-M光催化降解的动力学特性进行了研究。根据吸附特性和表面光催化降解反应得到了G-M光催化降解过程的动力学方程:1/r=1.744/C 0.1034。由半衰期法对动力学方程的讨论,发现实测值与计算值的差是由于中间产物在催化剂表面上与G-M的竞争,降低了催化剂对G-M有效降解的程度。对于不同初始浓度,其动力学方程近似表达成3种不同的形式。     

钠离子对合成愈创木酚催化剂的影响

在微型固定床连续流动反应装置上评价催化剂,研究了碱金属离子对合成愈创木酚催化剂AlPTiSbO性能的影响,结果显示碱金属离子对催化剂有较大的影响。优化了催化剂中钠离子的含量,发现最佳的钠铝原子比为0．045。在此催化剂上,280℃,常压下,愈创木酚的选择性为98％,邻苯二酚的转化率达到92％,催化剂稳定性也明显增加。采用BET,XRD,XPS和NH3-TPD等技术对催化剂进行了表征。结果显示,添加钠离子后,催化剂的比表面积有所增加;催化剂中磷酸盐（钠）含量增加;催化剂的表面酸强度降低。     

Benzoyl cyanide and mandelonitrile benzoate in the defensive secretions of millipedes

Analyses of the defensive secretions of 17 species of polydesmoid millipedes show that other chemicals besides HCN and benzaldehyde are liberated during cyanogenesis. Several members of the families Polydesmidae, Paradoxosomatidae, and Euryuridae are shown to secrete both phenol and guaiacol, with one paradoxosomatid also producing ethyl benzoate and benzoic acid. Also, members of the family Xystodesmidae commonly produce the three following compounds: benozoic acid, mandelonitrile benzoate, and benzoyl cyanide. Benzoyl cyanide has not been found previously as a natural product. The defensive role of these additional natural products as antipredator and antibiotic agents is discussed. For certain predators benzoyl cyanide in particular seems to possess anaesthetic properties. Our studies provide an initial chemotaxonomic basis for distinguishing between various polydesmoid taxa.     

重氮盐水解制备愈创木酚的实验工艺研究

概述了邻甲氧基苯重氮盐水解制备愈创木酚的机理,指出了反应所需的基本条件。通过单一因素实验研究,考察了水解温度、重氮盐稀释倍数和滴加时间、水酸质量配比、催化剂用量等对水解产品收率的影响,弥补了对重氮盐水解制备愈创木酚工艺进行详细研究的空白。结果表明,水解温度和催化剂用量对产品收率影响显著,重氮盐的稀释倍数、滴加速度和水解液中水酸配比有最佳值。     

不同催化剂催化裂化愈创木酚的性能

以分子筛为活性组分、高岭土为载体制备HZSM-5/K,HZSM-5/MK,HY/K,5A/K 4种催化剂,采用FTIR技术对催化剂的表面酸性进行表征。以愈创木酚为模型化合物,在480~560℃、WHSV=3~6 h-1条件下的固定床反应器中考察4种催化剂的催化裂化性能。实验结果表明,催化剂表面酸量大小的顺序为:HY/KHZSM-5/K≈HZSM-5/MK5A/K;愈创木酚裂化过程中主要生成苯酚、甲基苯酚、乙基苯酚等单环芳烃和多环芳烃,在540℃、WHSV=4 h-1条件下单环芳烃产率较高,焦炭产率较低;HZSM-5/MK,HZSM-5/K,HY/K,5A/K 4种催化剂作用下得到的单环芳烃产率依次为57.14%,51.65%,36.74%,30.00%,焦炭产率大小的顺序为:5A/KHY/KHZSM-5/K≈HZSM-5/M K。     

Anaerobic toxicity and biodegradability of pulp mill waste constituents

Batch bioassays have been conducted to characterize the response of methanogenic bacteria to several constituents of sulfite evaporator condensate. The results can be grouped into three ranges with increasingly severe consequences to anaerobic reactors: a low concentration, no effect range; a medium concentration range where methanogenesis is temporarily interrupted or slowed down, but may return to normal; and a high concentration range where methanogenesis is permanently inhibited. In some cases the toxicant was metabolized when present in the lower concentration ranges. There was also evidence that mechanisms other than fermentation to methane were significant in accounting for removal of the toxicants from solution. Organisms acclimated to low concentrations of a toxicant are better able to withstand a shock load of that toxicant than are unacclimated organisms.     

5-硝基愈长木酚的合成

5-硝基愈创木酚作为高效、低毒植物调节剂,一直倍受关注.它的合成目前主要采用愈创木酚硝化法,以发烟硝酸和冰醋酸混酸做硝化剂.本文由愈创木酚为起始原料,经酚酯化、硝化、水解等步骤合成了5-硝基愈刨木酚.酚酯化采用碱催化法,收率可达96%以上;硝化反应则采用乙酸酐和硝酸混合物为硝化剂.5-硝基愈创木酚最高收率可达到91%.