分子筛稳定的Cu物种催化乙醇脱氢制乙醛（英文）

生物乙醇作为一种绿色原料,常用于制备具有更高附加值的化学品,如乙烯、丙烯、丁二烯、1-丁醇和乙醛等.其中,乙醛作为重要的化学原料又可以进一步转化生成乙酸,乙酸酯和季戊四醇等。因此,由生物乙醇脱氢制乙醛的可持续路线受到了研究者的广泛关注.在众多催化体系中,Cu基催化剂表现出较高的活性和乙醛选择性,但Cu物种的烧结又会导致催化剂的快速失活.因此,抑制Cu物种的烧结是提高Cu基催化剂稳定性的常用手段.本文通过后合成路线构筑了具有限域效应的Cu/Beta分子筛催化剂,并成功应用于乙醇脱氢制乙醛反应.我们首先考察了Cu的负载量、反应温度和Cu的前驱体对反应的影响,发现以醋酸铜为前驱体的5%Cu/Beta催化剂在乙醇脱氢制乙醛反应中表现出最佳催化性能:催化剂寿命达到100 h,乙醛收率稳定在70%左右(反应条件:300℃,WHSV=1.0 h^-1).XRD,TEM,DRIFT,1H MAS NMR,UV-Vis以及H2-TPR等结果表明以醋酸铜为前驱体的Cu/Beta分子筛上的主要活性中心为CuO物种,并且该物种以高度分散的形式限域在分子筛脱铝产生的硅羟基缺陷位上.因此,在乙醇脱氢制乙醛反应中,限域的Cu/Beta分子筛催化剂与孤立的CuO催化剂相比,具有优异的抗烧结能力.然而,当反应至180 h时,催化剂会有明显的失活现象.再生后,尽管催化剂的初始活性能较好的恢复,但催化剂的寿命却大大下降.我们利用TEM,TGA以及CO-DRIFTS对反应后的催化剂进行表征,发现失活的Cu/Beta催化剂上存在Cu+和Cu0物种,并且伴有大块烧结现象.这表明随着反应的进行,Cu/Beta催化剂上的CuO物种会逐渐还原成Cu+和Cu0物种,而Cu0物种的出现又会诱导烧结现象的发生,进而导致催化剂的失活.

Investigation and Analysis of Soil Pollution of Heavy Metals(Hg,As) in Duanzhou District,Zhaoqing City

The soil heavy metals(Hg and As)in Duanzhou District of Zhaoqing City were determined by AFS200 T atomic fluorescence spectropho-tometer,and the soil environment in Duanzhou District was evaluated by several evaluation methods of soil heavy metal pollution,such as single factor index method,pollution load index method and Nemerow comprehensive pollution index method.Finally,according to the data and conclu-sions,the soil pollution situation in Duanzhou District of Zhaoqing was analyzed.The results will let more people pay attention to the changes of the environment and realize the harm of the environment,and the government can formulate a new plan conducive to the coordinated development of the environment and economy.

Ecological Investigation and Ecological Security Assessment of Xizhijiang River Basin in Huizhou City of Guangdong Province

In addition to such ecological problems as the pollution of the water system,the unreasonable structure of the upstream Basin and the insufficient water conservation forests,the Xizhi River Basin also faces human decision-making problems such as imperfect ecological compensation mechanism.In view of the above problems,using the DPSIR model(Drivers,Pressures,States,Impacts,Responses),this paper analyzed eucalyptus forest in Xizhi River Basin to assess the security of the Xizhi River ecological Basin,and finally concluded that the ecological status of Xizhi River Basin remains safe.

Removal Effect of Nitrifying Bacteria on Ammonia Nitrogen in Water

[Objectives]To investigate the removal effect of nitrifying bacteria on ammonia nitrogen in water.[Methods]In this experiment,the treated water(referred to as raw water hereinafter)from the Changping Town Qiaoli Water Treatment Project in Dongguan City of Guangdong Province was used as the experimental water body,and the nitrifying bacteria liquid used in the project was taken as the experimental material,to explore the removal effect of the nitrifying bacteria liquid on the ammonia nitrogen in the water body.[Results]Under the condition that other variables remain unchanged,the more the amount of nitrifying bacteria liquid added,the higher the removal efficiency of nitrifying bacteria liquid;under the same conditions,the removal effect of ammonia nitrogen in a stirred water body is better than that in an unstirred water body;the removal effect of ammonia nitrogen in a water body with bio-media/carriers is better than that without bio-media/carriers.[Conclusions]Nitrifying bacteria have a better removal effect on the ammonia nitrogen in the water body.

Investigation and Evaluation on Water Environment Quality of Xiawan Reservoir and Its Adjacent Waters in Zhaoqing

Town Planning Board of Zhaoqing passed the Planning and Design of Xiawan Urban Wetland Park in Zhaoqing City in 2012,and Xiawan Reservoir,located at the junction of Duanzhou District and Dinghu District,would be built into a wetland park at that time.To understand water quality status near the wetland park,according to relevant requirements of the Technical Guidelines for Environmental Impact Assessment:Surface Water Environment(HJ/T 2.3-93),the Environmental Quality Standards for Surface Water(GB 3838-2002),and the Technical Specification for Environmental Monitoring issued by the State Environmental Protection Administration,Xiawan Reservoir,Houlichong and the Xijiang River were investigated,monitored and evaluated.