CeO_2/Al_(0.2)Ti_(0.6)Zr_(0.2)O_(1.9)/ATS复合脱硝催化剂的制备及其抗硫抗水性能研究

将预先经酸处理的铝钛硅(ATS)多相陶瓷片先后负载Al0.2Ti0.6Zr0.2O1.9复合氧化物与CeO2活性组分,制得新型CeO2/Al0.2Ti0.6Zr0.2O1.9/ATS复合脱硝催化剂。运用X射线衍射(XRD)、扫描电镜(SEM)手段对该催化剂进行表征,研究催化剂的晶相、微观形貌。评价了催化剂的脱硝活性,研究了H2O和SO2对其脱硝活性的影响。实验结果表明,CeO2/Al0.2Ti0.6Zr0.2O1.9/ATS具有良好的脱硝活性,高活性温度窗口在100～350℃,当反应温度为250℃时,NO的转化率达98.49%。SO2和H2O在一定程度抑制该催化剂的低温脱硝活性,但随着温度的升高,其脱硝活性逐渐恢复。催化剂中活性组分CeO2具有储硫作用,当有SO2存在时,活性温度窗口向高温区偏移了100℃,在250～400℃时,H2O的存在反而提高了催化剂的脱硝活性。     

Fe_3O_4/ZrO_2-H_2O_2非均相类Fenton体系对3,4-二氯三氟甲苯的降解

以浸渍法制备的新型纳米Fe3O4/Zr O2为催化剂,3,4-二氯三氟甲苯(3,4-DCBTE)为目标污染物,用Fe3O4/Zr O2-H2O2非均相类Fenton体系对目标污染物进行降解,考察催化剂的催化效果和温度、pH、H2O2投加量和掺杂比等因素对催化剂催化效果的影响。结果表明,以纳米Fe3O4/Zr O2作为催化剂的非均相类Fenton体系对3,4-二氯三氟甲苯的处理效果极佳;随着温度的升高,纳米Fe3O4/Zr O2的催化效果不断提高;当pH降低时,催化剂的催化效果有明显提升,原始pH(pH=5.7)时反应去除效果最佳,去除率可达88.6%;催化剂用量的增加同样可以提高3,4-二氯三氟甲苯的降解效率;催化剂中Fe3O4∶Zr O2的物质的量比为1∶2时效果较其他掺杂比的催化剂效果更好,去除率最终可以达到96.82%;当H2O2投加量增加时,3,4-二氯三氟甲苯的降解效率先提高后降低,投加量为0.3 m L时去除效果最好,几乎可以完全去除目标有机物。以Fe3O4/Zr O2-H2O2非均相类Fenton体系处理3,4-二氯三氟甲苯时,目标污染物的降解符合一级反应动力学。     

钾掺杂对铈锆固溶体催化性能的影响

为研究钾掺杂对铈锆固溶体催化性能的影响,以Ce0.7Zr0.3O2为基体制备了一系列钾掺杂的铈锆固溶体xK-Ce0.7Zr0.3O2(x=0.05、0.10、0.15、0.20、0.25、0.30)催化剂样品,通过程序升温氧化(TPO)过程进行活性评价,并通过XRD、BET、H2-TPR和O2-TPD进行分析表征。结果表明,采用溶胶凝胶法制备的催化剂的催化性能比络合燃烧法所制备的稍好;当钾的掺杂量为0.10≤x≤0.30时,xK-Ce0.7Zr0.3O2催化碳烟颗粒燃烧的活性得到提高,起燃温度和最大燃烧速率温度分别在315℃和375℃附近,明显优于Ce0.7Zr0.3O2;掺杂钾后的催化剂样品均能形成萤石结构,并且随钾掺杂量的增大比表面积减小。     

MgO-ZrO_2固体碱催化废弃动物油制备生物柴油

采用稀释共沉淀法制备了Mg O-Zr O2固体碱催化剂,通过催化预处理低酸值油的酯交换反应来制备生物柴油。采用BET、SEM、XRD等方法对催化剂进行表征。主要研究了固体碱制备中Mg O-Zr O2物料比和煅烧温度对催化剂催化活性的影响,通过对比发现:制备的催化剂孔径均在2~10 nm之间,Zr O2以单斜晶相微晶形式存在并很好地分散于Mg O相中,表现出较高的催化活性。当固体碱中Mg/Zr物料比为3∶1,煅烧温度为500℃时催化剂的活性最佳,通过对酯交换反应影响因素的考察得到了催化反应的最佳工艺条件;酯交换率达到96.9%。     

SO_2对Zr掺杂Mn-Ce/GR催化剂低温脱硝性能的影响

通过水热法分别制备掺杂Zr、Sb、Sn和Si的Mn-Ce/石墨烯(Mn-Ce/GR)催化剂,考察了其在低温氨气选择性催化还原(NH_3-SCR)过程中对NO_x的去除效率和抗SO_2中毒性能。结果显示,掺杂Zr后,催化剂具有良好的低温脱硝活性,在120℃时,其NO_x转化率和N_2选择性分别达到97.26%和98.97%,且当进气中SO_2的体积分数为200×10~(-6)时,其抗硫性明显优于掺杂其他3种元素的催化剂,原因是硫酸盐在掺杂Zr催化剂表面的沉积速率有所减缓。通过Raman、XRD、HRTEM、SEM、BET、XPS、FT-IR、H_2-TPR以及NH_3-TPD等表征手段对掺杂Zr的Mn-Ce/GR新鲜催化剂和失活样品进行表征分析。发现,SO_2对掺杂Zr催化剂的毒化作用主要有4个方面:Oα大量减少,还原能力减弱;活性组分CeO_2含量减少,储氧能力减弱;催化剂表面Zr含量减少,酸性位点减少;硫酸盐和硝酸盐在催化剂表面大量沉积,减少了催化剂的比表面积。     

TiO_2/AC复合催化剂的制备及其对六氯苯的光催化降解性能研究

以颗粒活性炭（AC）和钛酸丁酯为原料,采用微波辐射法制备TiO2/AC复合光催化剂,并对制备的催化剂进行了表征;采用该催化剂对六氯苯进行光催化降解,确定了六氯苯降解的最佳工艺条件,并就几种外加试剂对TiO2/AC光催化降解六氯苯的强化作用进行了探讨。结果表明,制备的催化剂中TiO2均匀分布在活性炭表面、呈单一的锐钛矿晶型,晶粒生长完善。该催化剂催化降解六氯苯的最佳工艺条件为：pH值为5、TiO2负载量为18.2%、TiO2/AC投加量为0.4 g/L、反应时间为60 min。在此条件下,六氯苯降解效率达90.3%。添加适量的H2O2、AgNO3、K2S2O8、KIO4和KMnO4均能提高TiO2/活性炭对六氯苯的光催化降解效率。5种外加试剂的适宜添加量分别为0.3%、1.0、1.0、0.1和0.1 mmol/L,对TiO2/AC光催化效率的强化作用大小顺序为：H2O2〉AgNO3〉K2S2O8〉KMnO4〉KIO4。     

Zn_(0.9)Fe_(0.1)S硫化物的制备及其光催化降解双酚A的性能

以沉淀法制备的Zn0.9Fe0.1S硫化物为光催化剂,双酚A(BPA)为目标污染物,在紫外光下建立UV+硫化物+H2O2光催化体系。采用扫描电子显微镜(SEM)、X射线衍射仪(XRD)、比表面积测试(BET)对催化剂微观形貌进行分析,并考察了过氧化氢加入量、初始pH、BPA初始浓度、催化剂用量等因素对BPA降解率的影响,研究了该硫化物催化剂的使用寿命。结果表明:当pH=5,过氧化氢的加入量=0.20 mmol·L~(-1),BPA初始浓度为10 mg·L~(-1),催化剂的加入量为0.08 g时,对BPA的去除率最高,达90%以上。催化剂连续使用7次后,对BPA的降解率仍然能达到80%。说明该硫化物催化剂具有较好的稳定性并且与H2O2在光催化作用下具有良好的协同作用,而催化剂的加入也极大地提高了光催化工艺对BPA的处理效果。相比传统光-Fenton体系,UV+硫化物+H2O2光催化体系不仅可以提高BPA的降解率,还降低了H2O2的使用量,降低处理成本。     

CuO/TiO2-H2O2可见光催化亚甲基蓝脱色效果及影响因素研究

以水解法制备的锐钛矿型TiO2为载体,制备了CuO/TiO2型光催化剂.以亚甲基蓝为对象,在可见光照射下研究了H2O3加入量、pH值和催化剂投加量对脱色效果的影响,同时与改性前的TiO2催化剂进行了脱色效果的对比.结果表明亚甲基蓝在碱性条件下能较好脱色,H2O2用量和CuO/TiO2催化剂投加量分别为每1 000 mL反应液各加入10 mL和0.1 g时脱色最好;另外,TiO2催化剂也在碱性条件下能较好脱色,H2O2用量和催化剂投加量分别为每1 000 mL反应液各加入12.5 mL和0.1 g时脱色最好.最优条件下对比实验表明,CuO/TiO2型催化剂在可见光照射下具有很高的催化活性,亚甲基蓝2 h脱色率达到88%,远好于改性前的TiO2和Degussa P25催化剂.     

La-K-Co-Mn-O钙钛矿型复合氧化物同时去除碳颗粒和Nox的性能

采用柠檬酸络合燃烧法合成制备了La1-xKxCo0.5Mn0.5O3(x为K+取代量,x=0、0.1、0.2、0.3、0.4、0.5)系列钙钛矿型复合金属氧化物催化剂,以X射线衍射、红外光谱和比表面积等手段对该催化剂进行表征,以常压固定床微型反应器程序升温氧化还原反应技术评价该催化剂同时去除模拟柴油机尾气中炭黑颗粒(表征柴油机尾气中的碳颗粒)和NOX的催化性能.结果表明,K+部分取代LaCo0.5Mn0.5O3中的La3+后,催化剂催化性能得到明显改善,炭黑颗粒的起燃温度(Tig)、峰值温度(Tm)和燃尽温度(Tf)均降低,NOX的转化率提高,最高为16.6%;La0.6K0.4Co0.5Mn0.5O3具有最佳的催化性能,炭黑颗粒的Tig、Tm和Tf分别为305、350、379 ℃,炭黑颗粒燃烧产物中CO2的体积分数为98.8%,NOX转化率为15.5%.     

应用于微波处理正丁酸模拟废水的催化剂制备及表征

通过正交实验对镍铁铈(Ni-Fe-Ce)、镍铁钛(Ni-Fe-Ti)、镍铁锆(Ni-Fe-Zr)3组复合催化剂的共沉淀-焙烧法制备工艺进行优化,并对优选出的催化剂进行SEM和XRD表征。结果表明,镍铁锆催化剂是最优催化剂,最佳制备条件为Ni∶Fe(摩尔比)0∶10、Zr∶Fe(摩尔比)4∶1、干燥时间6 h、焙烧温度350℃、焙烧时间6 h、沉淀时间5 h;此条件下制备的Fe-Zr催化剂的催化效能最高,TOC去除率达到75%;Zr的掺和改变了Fe催化剂的物相,进而提高了Fe催化剂的催化活性。     

The effects of manganese precursors on Mn-based/TiO2 catalysts for catalytic reduction of NO with NH3

Manganese acetate (MnAc) and manganese nitrate (MnN) were employed as precursors for the preparation of MnAc)/TiO2, Mn (N)/TiO2, Mn(Ac)-Ce/TiO2, and Mn(N)-Ce/TiO2 by impregnation. These complexes were used as catalysts in the low-temperature selective catalytic reduction of NO with NH3. The influence of manganese precursors on catalyst characteristics, the reduction activity, and the stability of the catalysts to poisoning by H2O and SO2 were studied. Experiments showed that Mn(N) produced MnO2 with large grain sizes in Mn(N)/TiO2 catalyst. On the contrary, Mn(Ac) led to highly dispersed and amorphous Mn2O3 in Mn (Ac)/TiO2 catalyst, which had better catalytic activity and stability to SO2 at low temperatures. The doping of cerium reduced the differences in catalytic performance between the catalysts derived from different Mn precursors.     

Evaluation of Cu-PPHs as active catalysts for the SCR process to control NOx emissions from heavy duty diesel vehicles

Copper based catalysts supported on mesoporous materials, which were in turn based on a surfactant expanded zirconium phosphate for the formation of silica galleries in the interlayer space, were prepared by the impregnation method. They were then characterised and tested in the selective catalytic reduction of NO with ammonia as active catalysts for the control of the NOx emissions from heavy duty vehicles. Copper catalysts displayed a high catalytic performance, even in the presence of 14% (v/v) of H2O and 100 ppm of SO2. They also displayed improved catalytic behaviour when compared to a CuZSM5 catalyst.     

Characterization and reactivity of natural manganese ore catalysts in the selective catalytic oxidation of ammonia to nitrogen

Natural manganese ore (NMO) catalysts were characterized and tested in the selective catalytic oxidation of ammonia to nitrogen oxides under dilute conditions. Also, the oxidation of ammonia (NH(3)) was carried out using pure MnO(2), Mn(2)O(3) for comparing with the activity. It is found that the activity of NMO was similar to that of MnO(2) at low temperature below 150 degrees C but above this temperature, the activity of these catalysts showed the difference. In the course of NH(3) oxidation, N(2), NO, N(2)O and H(2)O were produced. But the quantity of NO(2) produced in this experiment was negligible. At temperature below 250 degrees C, selectivity into N(2) from NH(3) oxidation was in the order, NMO > MnO(2) > Mn(2)O(3). This is the reverse of activity of these manganese oxides. Also the characterization of NH(3) oxidation was proposed and supported by the effect of space velocity, inlet O(2) and NH(3) concentration. The increase of space velocity remarkably influenced not only the conversion but also selectivity into N(2). The higher the reaction temperature was, the higher the effect of inlet O(2) and NH(3) concentration on the reaction rate was. By introducing NO during NH(3) oxidation reaction, the possibility of NMO as selective catalytic reduction catalyst at low temperature was studied and showed positive results.     

Fe2O3-Cr2O3/TiO2系列催化剂的结构和脱硝性能

研究以纳米TiO2为载体,浸渍负载过渡金属氧化物,以CO为还原剂的脱硝催化剂的脱硝性能。实验中以计算量的Ni（NO3）2和Fe（NO3）3混合溶液浸渍纳米TiO2粉末,室温下搅拌30 min至混合均匀,放入旋转蒸发器中,70℃下至水分蒸干为止;所得粉末在550℃下、空气气氛中焙烧4 h即得所需催化剂。用以上方法分别制备2%Fe2O3-10%Cr2O3/TiO2、4%Fe2O3-8%Cr2O3/TiO2、6%Fe2O3-6%Cr2O3/TiO2、8%Fe2O3-4%Cr2O3/TiO2与10%Fe2O3-2%Cr2O3/TiO2等5种催化剂样品。实验结果表明,制备的催化剂具有较好的结构,分散较为均匀。对于CO＋NO反应,Fe2O3-Cr2O3/TiO2系列催化剂具有较好的催化活性,NO的转化率都达到了100%。其中,10%Fe2O3-2%Cr2O3/TiO2样品具有最好的低温活性,H2-TPR结果表明,这是由于10%Fe2O3-2%Cr2O3/TiO2催化剂更易于被CO预还原。     

CuCoOx／TiO2催化氧化NO性能研究

采用浸渍法制备了CuCoOx／TiO2催化剂,考察了焙烧温度、反应温度、氧含量、NO浓度和空间速度对催化剂催化氧化NO性能的影响,并考察了催化剂的抗硫抗水性能。XRD、TPR和BET分析表明,350℃焙烧的催化剂具有CuCo2O4尖晶石结构,比表面积大,对NO的氧化效果好。在空速为5000h^-1,NO进口浓度500mg／m^3,含氧量10％的条件下,反应温度300℃时NO转化率可达79．5％,250℃时NO转化率接近50％。该催化剂具有良好的单独抗SO2、抗H2O毒化性能,H2O和SO2同时存在时很快失活。该催化剂可用于不同时含H2O和SO2的含NO气体催化氧化后再吸收处理。     

微量Pd对CrOx／ZrO2催化剂催化活性的影响

运用微反技术考察了ＣｒＯＸ负载型催化剂对ＣＯ＋Ｏ２和ＣＯ＋ＮＯ反应的催化活性。研究了微量Ｐｄ加和ＣｒＯＸ基双组元催化剂对上述反应的催化活性,中间产物Ｎ２Ｏ生成和Ｎ２生成的影响。     

A review of the catalysts used in the reduction of NO by CO for gas purification

The reduction of NO by the CO produced by incomplete combustion in the flue gas can remove CO and NO simultaneously and economically. However, there are some problems and challenges in the industrial application which limit the application of this process. In this work, noble metal catalysts and transition metal catalysts used in the reduction of NO by CO in recent years are systematically reviewed, emphasizing the research progress on Ir-based catalysts and Cu-based catalysts with prospective applications. The effects of catalyst support, additives, pretreatment methods, and physicochemical properties of catalysts on catalytic activity are summarized. In addition, the effects of atmosphere conditions on the catalytic activity are discussed. Several kinds of reaction mechanisms are proposed for noble metal catalysts and transition metal catalysts. Ir-based catalysts have an excellent activity for NO reduction by CO in the presence of O₂. Cu-based bimetallic catalysts show better catalytic performance in the absence of O₂, in that the adsorption and dissociation of NO can occur on both oxygen vacancies and metal sites. Finally, the potential problems existing in the application of the reduction of NO by CO in industrial flue gas are analyzed and some promising solutions are put forward through this review.

     

Mn的氧化价态对Mn／γ-Al2O3催化剂催化臭氧氧化气相低浓度甲苯的影响

采用共沉淀法,以Al2O3为载体制备Mn／γ-Al2O3和Mn—Ce／Mn／γ-Al2O3催化剂,并分别在N2气氛和O2气氛下焙烧。采用固定床连续流动反应器,研究所制备催化剂在室温条件下催化臭氧氧化甲苯的性能。通过XRD、XPS和FTIR等手段对催化剂的结构和组成进行表征。结果表明,Mn／Mn／γ-Al2O3催化剂具有良好的催化臭氧氧化甲苯和催化臭氧自身分解的性能,共沉淀法制备催化剂的最佳Mn负载量为20％。O2气氛焙烧和Ce的加入,可以有效提高催化剂的活性和寿命。原因是O2气氛焙烧和Ce的加入可以提高Mn的氧化价态。催化剂失活的主要原因是有机副产物在催化剂表面吸附堆积,失活催化剂在550℃、空气气氛下焙烧可恢复催化性能。     

催化法脱除NO_x的研究进展

如何有效地脱除氮氧化物是目前空气污染治理的一个重点和难点 ,催化还原和催化分解是目前研究得较多的脱除氮氧化物方法。本文从催化剂创新和催化反应体系的发展等方面对上述过程研究、应用情况进行了总结 ,并根据作者的认识进行了适当的评述。