共沉淀法制备铜系催化剂及其稳定性的研究

主要介绍了利用共沉淀方法制备铜系催化剂,并考察了制备过程中各个工艺参数对铜系催化剂稳定性的影响。通过优化催化剂的设计和制备方法,可有效地改善Cu2+的溶出问题,使该类催化剂具有广阔的应用前景。     

Pyrolysis of low-density polyethylene using synthetic catalysts produced from fly ash

Catalytic pyrolysis of low-density polyethylene (LDPE) was investigated using various fly ash-derived silica–alumina catalysts (FSAs). FSAs were prepared by a simple activation method that basically includes NaOH treatment of fly ash by a fusion method, followed by an aging process. A series of LDPE pyrolysis experiments was conducted and the catalytic performance of FSAs was assessed in terms of the degradation temperature and the simulated boiling point distribution of the liquid products. The effects of synthesis conditions such as NaOH/fly ash weight ratio and aging time were examined by X-ray diffractometer (XRD), Brunauer-Emmett-Teller (BET) surface area analyzer, and scanning electron microscope to clarify the controlling factors affecting the catalytic activity. To obtain catalyst with high activity, it is necessary to produce sufficient silica and alumina species that can be easily co-precipitated into solid acid catalyst by destruction of the fly ash structure and to optimize the activation time for catalyst synthesis to prevent the transformation into inactive phases. The catalytic performance of FSA obtained from optimal conditions was equivalent to that of commercial catalysts, demonstrating the effectiveness of the catalyst.     

均相/异相催化剂光降解垃圾渗滤液效果的研究

垃圾渗滤液是一种复杂有毒的、生化降解性差的高浓度有机废水,高级氧化技术具有氧化能力强和无二次污染等特点,被认为是处理难降解有机污染物最有应用前景的方法.本研究在500 W汞灯、25℃、2.5 h反应条件下,对比了TiO_2、K2S2O_8、K2S2O_8/Fe2+、施氏矿物、施氏矿物/H2O_2、Fe2+/H2O_26种催化剂组合光化学处理垃圾渗滤液的效果.结果表明,施氏矿物/H2O_2和Fe2+/H2O_2光催化降解垃圾渗滤液中有机污染物的效果优于其它催化剂组合,渗滤液中CO_D去除率分别为41.6%和46.5%,TO_C去除率分别为76.0%和78.1%.然而,Fe2+/H2O_2组合在光催化处理垃圾渗滤液后会产生大量难以沉降的Fe(O_H)3絮状物,且渗滤液色度明显增加,由初始的40倍上升到175倍.而施氏矿物/H2O_2组合则避免了上述问题,色度去除率达100%,被认为是一种具有应用前景的光化学降解垃圾渗滤液的催化剂组合.     

我国电石法生产聚氯乙烯行业汞排放清单

提出了我国电石法聚氯乙烯(PVC)生产全生命周期汞排放清单的计算方法。采用低汞触媒有盐酸脱吸工艺、高汞触媒有盐酸脱吸工艺、高汞触媒无盐酸脱吸工艺的汞输入因子分别为0.045 g/kt、0.091 g/kt和0.122 g/kt,回收产品的汞输出分布因子分别为95.37%、81.97%和97.18%。估算得到:2010年我国电石法PVC生产汞输入量792.8~814.8 t;回收的产品汞705.9~724.4 t,通过大气无组织排放、管道残留以及其他未知途径汞排放79.6~82.8 t;废水汞排放1.3 t;固体废物汞排放3.6~3.7 t;废酸汞排放2.5~2.6 t。回收的产品汞是汞输出的主要途径。     

MTO废催化剂SAPO-34的再生

采用干凝胶转化法对甲醇制烯烃(MTO)废催化剂SAPO-34进行再生,将SAPO-34分子筛晶化所需的硅、铝、磷原料同时作为黏结剂使用,经干凝胶转化制备出再生催化剂,并对催化剂进行了表征及MTO反应活性评价。表征结果显示,再生催化剂的晶体结构、微观形貌、粒径分布、孔结构、耐磨性及酸中心均得到了恢复与改善,磨损指数可达0.35%/h。实验结果表明:在催化剂加入量为1.0 g、进气中甲醇质量分数为95%、甲醇质量空速为3 h-1、反应温度为450℃、反应压力为常压的条件下,再生催化剂的甲醇转化率接近100%,双烯(乙烯和丙烯)选择性较废催化剂提高了约3百分点,可达87%以上;同时,再生催化剂的寿命也较废催化剂有了明显改善。     

Ni,Co掺杂对Mn-Ce/TiO_2催化剂脱硝活性的影响

以Ti O_2为载体,采用浸渍法制备Ni或Co掺杂的Mn-Ce/Ti O_2催化剂,用于烟气的选择性催化还原法低温脱硝。考察Ni或Co的掺加对Mn-Ce/Ti O_2催化剂活性的影响,并对各催化剂进行了BET,XRD,H_2-TPR,XPS表征。实验结果表明:在NO,NH_3,O_2的体积分数分别为6×10~(-4),6×10~(-4),6×10~(-2),空速为16 000 h~(-1)的条件下,Mn-Ce/Ti O_2、Mn-Ce-Ni_(0.4)/Ti O_2和Mn-Ce-Co_(0.2)/Ti O_2催化剂的NO去除率在120℃时分别为38%,68%,74%,在150℃时分别为64%,92%,近100%,这表明掺加Ni或Co后Mn-Ce/Ti O_2催化剂的脱硝活性明显提高;在进气中加入体积分数为1×10~(-4)的SO_2后,Mn-Ce/Ti O_2催化剂的NO去除率在300 min内从98.2%下降至57.2%,而Mn-CeCo_(0.2)/Ti O_2和Mn-Ce-Ni_(0.4)/Ti O_2催化剂的NO去除率分别为73.9%和69.8%,这表明Ni或Co的掺加有助于提高催化剂的抗硫性能。表征结果表明:Ni或Co的掺加基本不影响Mn和Ce在载体Ti O_2上的分散;Ce元素以Ce~(3+)和Ce~(4+)价态存在,且主要为Ce~(4+);催化剂的比表面积变化不大;Mn O_x与Ce O_x的结晶度降低,催化剂的氧化还原能力增强。     

Removing lignin model pollutants with BiFeO3–g-C3N4 compound as an efficient visible-light-heterogeneous Fenton-like catalyst

BiFeO_3–g-C_3N_4 nanoscaled composite was prepared with a hydrothermal method and evaluated as a highly efficient photo-Fenton like catalyst under visible light irradiation. The BiFeO_3–g-C_3N_4 composite exhibited much stronger adsorption ability to lignin model pollutant(guaiacol) than that of BiFeO_3, which may be due to the higher specific surface area(BiFeO_3–g-C_3N_4: 35.59 m~2/g BiFeO_3: 7.42 m~2/g) and the adsorption form of π–π stack between g-C_3N_4 and guaiacol. The composite exhibited excellent visible light-Fenton like catalysis activity, being influenced by the solution pH value and the proportions of BiFeO_3 and g-C_3N_4 nanosheets. Under optimal conditions with visible light irradiation, the BiFeO_3–g-C_3N_4 composite yielded fast degradation of guaiacol with an apparent rate constant of 0.0452 min~(-1), which were 5.21 and 6.80 folds of that achieved by using BiFeO_3 and the mixture of BiFeO_3 and g-C_3N_4 nanosheets, respectively. The significantly enhanced visible light-Fenton like catalytic properties of the BiFeO_3–g-C_3N_4 composite in comparison with that of BiFeO_3 was attributed to a large surface area, much increased adsorption capacity and the semiconductor coupling effect between BiFeO_3 and g-C_3N_4 in the composite.     

基于新型陶粒催化剂的H_2O_2/O_3多相催化氧化体系降解刚果红的研究

用自制陶粒催化剂与臭氧(O_3)、双氧水(H_2O_2)构建多相催化氧化体系降解水中的刚果红。采用电镜扫描、能谱分析与红外光谱等表征了陶粒催化剂,考察了反应时间、O_3浓度、H_2O_2投加量等因素下多相催化氧化体系对刚果红色度和COD去除率。结果表明:自制的陶粒催化剂表面较为粗糙,比表面积较大,反应后的陶粒催化剂表面较为平滑,比表面积较反应前减少;自制陶粒催化剂对H_2O_2催化能力差,但对O_3、H_2O_2/O_3具有较好的催化效果。当O_3浓度在1.2~3.8 mg/L时,陶粒/H_2O_2/O_3体系较O_3、H_2O_2/O_3对刚果红(100 mg/L)的脱色率分别平均提高了11.72%、15.32%,COD去除率分别提高了16.37%、24.29%,将陶粒引入O_3、H_2O_2/O_3体系中可减少O_3和H_2O_2的用量,提高体系的氧化性能,降低运行成本。     

负载CuO/MnO海泡石中性条件催化H_2O_2处理铝材切削液废水

以改性海泡石为载体,采用浸渍-共沉淀法负载Cu0、MnO制备了中性条件下催化H_2O_2氧化催化剂(简称中性催化剂)。以铝材切削液废水为处理对象,研究了催化剂在中性条件下的催化性能,通过投加不同浓度的羟基自由基捕捉剂叔丁醇,对反应机理进行了探讨,同时研究了过氧化氢用量、催化剂用量等因素对废水COD去除率的影响。结果表明:在中性条件下,催化剂对铝材切削液废水具有较高的COD去除率,当过氧化氢用量为1.25 mol/L,催化剂用量为25 g/L,室温条件反应120 min时,COD去除率达到88%;经该方法处理后,废水ρ(BOD5)/ρ(COD)由处理前的0.09提升到处理后的0.36,可生化性得到了明显提高。     

N-TiO_2/RGO催化剂的制备及其光催化性能的研究

以三乙胺为氮源,HF为形貌控制剂,采用水热法一步合成了N掺杂(001)面锐钛矿TiO_2纳米片/还原氧化石墨烯(N-Ti O2/RGO)复合催化剂,通过XRD、FTIR、SEM、TEM和Raman对样品的组成结构和形貌进行表征。以罗丹明B(Rh B)为模拟污染物,研究了不同掺N量和氧化石墨烯加入量下制备的复合材料的光催化性能。实验结果表明:当n(N)∶n(Ti)为0.5,氧化石墨烯加入量为15 m L时,N-TiO)2/RGO复合材料的光催化性能最好。在催化剂用量为0.5 g/L,罗丹明B溶液初始浓度为20 mg/L时,紫外光催化反应30 min后,罗丹明B的降解率可达94.02%。