Effect of Different Loadings on the Performance of Ni2P/Al2O3 Catalysts for Low-Temperature Thioethering and Selective Hydrogenation of Diolefins in Liquefied Petroleum Gas

In this study,different loadings of x%Ni_(2)P/γ-Al_(2)O_(3)(x=6%,9%,12%,15%,18%)catalysts with aluminum oxide(Al_(2)O_(3))as the carrier,nickel chloride(NiCl2)as the nickel(Ni)source,and ammonium hypophosphite(NH_(4)H_(2)PO_(2))as the phosphorus(P)source were prepared by the equal volume impregnation method to investigate the effects of different loadings on the performance of the selective hydrogenation of diolefins and thiol etherification in LPG.The physicochemical properties of the catalysts were characterized by XRD,BET,SEM,TEM,H_(2)-TPR,and XPS,and the catalytic activity of the catalysts was evaluated in a fixed-bed microreactor.The results showed that a change in the loading affected the catalyst crystalline phase structure and size,specific surface area,P coverage,active phase dispersion,and catalytic activity.At 6%,9%,and 12%loadings the catalysts had an Ni phase but there was no obvious Ni_(2)P phase in the nickel phosphide;at 15%loading a single Ni_(2)P phase was obtained,and at 18%loading both Ni_(2)P and Ni1_(2)P_(5) phases appeared.There was a P enrichment on the catalyst surface,and the higher the loading the more P species were enriched on the surface,but some of the P was lost during the catalyst reduction process due to the production of phosphine(PH3)gas.The 15%Ni_(2)P/γ-Al_(2)O_(3) catalyst had the largest Ni/Al ratio and the best dispersion.The Ni_(2)P active phase size was small at about 4.25 nm and Ni_(2)P was uniformly dispersed on the catalyst surface without agglomeration.The 15%Ni_(2)P/γ-Al_(2)O_(3) catalyst had the best catalytic activity at a pressure of 2.0 MPa,a liquid hourly space velocity(LHSV)of 3.0 h-1,and a hydrogen to hydrocarbon ratio of 12.The 1,3-butadiene conversion was 97.45%and the methanethiol removal was 100%at a temperature of 140℃.

Influence of chromium modification on the properties of MnO_x-FeO_x catalysts for the low-temperature selective catalytic reduction of NO by NH_3

Catalytic properties of MnOx-FeOx complex oxide （hereafter denoted as Mn-Fe） catalysts modified with different loadings of chromium oxide were investigated by using the combination of physico-cbemical techniques, such as N2 physisorption, X-ray diffraction （XRD）, high-resolution transmission electron microscope （HRTEM）, in situ Fourier transform infrared spectroscopy （in situ FT-IR） and temperature-programmed reduction （TPR） and their catalytic activities were evaluated with the selective catalytic reduction （SCR） of NOx by NH3. It was found that with the addition of Cr, more NO could be removed in the low-temperature window （below 120 ℃）. Among the tested catalysts, Mn-Fe- Cr （2 ： 2 ： 1） catalyst exhibited the best catalytic performance at 80 ℃ with the NO conversion higher than 90%. The combination of the reaction and characterization results indicated that （1） the strong interaction among tertiary metal oxides existed in the catalysts when Cr was appropriately added, which made the active components better dispersed with less agglomeration and sintering and the largest BET specific surface area could be obtained; （2） Cr improved the low-temperature reducibility of the catalyst and promoted the formation of the active intermediate （-NH3＋）, which favored the low-temperature SCR reaction.

TiO_2-Supported Binary Metal Oxide Catalysts for Low-temperature Selective Catalytic Reduction of NO_x with NH_3

Binary metal oxide（MnOx-A/TiO2）catalysts were prepared by adding the second metal to manganese oxides supported on titanium dioxide（TiO2）,where,A indicates Fe2O3,WO3,MoO3,and Cr2O3.Their catalytic activity,N2 selectivity,and SO2 poisonous tolerance were investigated.The catalytic performance at low temperatures decreased in the following order：Mn-W/TiO2〉Mn-Fe/TiO2〉Mn-Cr/TiO2〉Mn-Mo/TiO2,whereas the N2 selectivity decreased in the order：Mn-Fe/TiO2〉Mn-W/TiO2〉Mn-Mo/TiO2〉Mn-Cr/TiO2.In the presence of 0.01%SO2 and 6%H2O,the NOx conversions in the presence of Mn-W/TiO2,Mn-Fe/TiO2,or Mn-Mo/TiO2 maintain 98.5%,95.8%and 94.2%, respectively,after 8 h at 120°C at GHSV 12600 h？ 1 .As effective promoters,WO3 and Fe2O3 can increase N2 selectivity and the resistance to SO2 of MnOx/TiO2 significantly.The Fourier transform infrared（FTIR）spectra of NH3 over WO3 show the presence of Lewis acid sites.The results suggest that WO3 is the best promoter of MnOx/TiO2,and Mn-W/TiO2 is one of the most active catalysts for the low temperature selective catalytic reduction of NO with NH3.

Low-Temperature Selective Catalytic Reduction of NO with NH_3 over Fe–Ce–O_x Catalysts

In this study,we used a simple impregnation method to prepare Fe-Ce-O_x catalysts and tested them regarding their low-temperature(200-300 ℃) selective catalytic reduction(SCR) of NO using NH_3.We investigated the effects of Fe/Ce molar ratio,the gas hourly space velocity(GHSV),the stability and SO_2/H_2O resistance of the catalysts.The results showed that the FeCe(1:6)O_x(Ce/Fe molar ratio is 1:6) catalyst,which has some ordered parallel channels,exhibited good SCR performance.The FeCe(1:6)O_x catalyst had the highest NO conversion with an activity of 94-99%at temperatures between 200 and300 ℃ at a space velocity of 28,800 h^(-1).The NO conversion for the FeCe(1:6)O_x catalyst also reached 80-98%between 200 and 300 ℃ at a space velocity of204,000h^(-1).In addition,the FeCe(1:6)O_x catalyst demonstrated good stability in a 10-h SCR reaction at200-300 ℃.Even in the presence of SO_2 and H_2O,the FeCe(1:6)O_x catalyst exhibited good SCR performance.

Fundamental study on utilization of tin and zinc-bearing iron concentrate by selective chlorination

The feasibility and technologies of comprehensive recovery of tin, zinc, arsenic and iron from the complex iron ores by selective chlorination roasting were studied by thermodynamic analysis and roasting experiments. Investigation shows that the product pellets with the compression strength of 2625N/P, the tumble index of 97.26%, the abrasion index of 1.35%, tin, arsenic and zinc residue of 0.043%, 0.046% and 0.058% respectively can be achieved if balling a concentrate containing 0.39% tin, 0.40% arsenic and 0.28% with addition of 8% coke breeze and 0.5% CaCl2 and roasting the pellets at 10601080℃ for 40min. The volatilization of tin, arsenic and zinc is 91.75%, 93.42% and 81.12% respectively. The performances of the product pellets are able to meet the requirements of blast furnace ironmaking.

The Preparation of Mn-Fe/CNTs Catalyst at the Low-Temperature Selective Catalytic Reduction of NO with NH₃

The metal oxide catalyst was prepared by loading MnOx and FeOx on carbon nano-tubes (CNTs) with impregnation method. Then the catalyst was characterized by BET and XPS, and the effect of adding FeOx on MnOx/CNTs catalyst at the low-temperature selective catalytic reduction of NO with NH3 was investigated. The results showed that the active components were loaded suc-cessfully and easily on the carriers by impregnation. The Mn-Fe/CNTs catalyst was chose 10% Fe(NO3)3 solution to impregnate Mn-Fe/CNTs. The species of active components loaded on the catalyst were Fe2O3. The different concentration of impregnant solution played an important role for NO conversion in SCR with NH3. With the increase of the concentration of impregnant solution, the NO conversion of catalysts was increasing initially then decreasing.

Vanadium extraction from vanadium-bearing titanomagnetite by selective chlorination using chloride wastes (FeClx)

Vanadium extraction of vanadium-bearing titanomagnetite was investigated by selective chlorination. Thermodynamics analyses on the interactive reactions among related species in the system were made before the experiments. Some fundamental experiments for extracting vanadium by FeCl_x as chlorinating agent were conducted over the temperature range of 900-1300 K under air or oxygen atmosphere. The results show that vanadium can be extracted by the selective chlorination, using FeCl_x, based on thermodynamic analysis and experiment. Vanadium extraction ratio first increases with the increase of temperature, and then decreases with the increase of temperature over the range of 900-1300 K under air or oxygen atmosphere. The higher molar ratio of FeCl_3 to oxides(n_(chl):n_(oxd)) reacting with FeCl_3, the higher ratio of vanadium extraction. Under oxygen atmosphere, the vanadium extraction ratio is up to 32% at 1100 K for 2 h by using FeCl_3 as chlorinating agent.

Low-Temperature SCR of NO with NH_3 on Mn-Based Catalysts Modified with Cerium

A series of Mn-based catalysts, MnOx, MnOx-CeO, Pd-Mn-Ce, MnOx/AC were prepared. And their performances for NO low-temperature SCR were investigated in this study. The NO conversion is about 90% at 100 ℃ on MnOx-CeOand almost all NO can be converted at 120 ℃. Similar results are also observed in the tests on MnOx-CeO/AC. The excellent low-temperature catalytic activity of modified Mn-based catalysts, which may be mainly due to the oxygen storage function of CeO, can improve the oxygen flow on the catalysts surface. Then the oxidation of NO to NO2 is accelerated, which is the key step of NO SCR.

Nano-SiO_(2)选择性分布对CPE增韧PVC体系的影响

通过改变混合顺序,研究了纳米二氧化硅(nano-SiO_(2))选择性分布对氯化聚乙烯(CPE)增韧聚氯乙烯(PVC)体系力学性能、流变性能、耐热性能的影响。结果表明:当nano-SiO_(2)分布于CPE相时,样品的拉伸强度、弯曲强度、弯曲模量、热变形温度提升更显著,当nano-SiO_(2)分布于PVC相时,样品的缺口冲击强度提升更显著,尤其在CPE用量较低时。nano-SiO_(2)选择性分布对样品的流变性能会产生影响,但对其玻璃化转变温度影响较小。

可控生长石墨炔/氢氧化钴异质界面用于高效产氯

氯碱工艺广泛应用于各种工业生产过程,在化工生产中起着关键和不可替代的作用。然而,目前所报道的析氯反应(CER)的电催化剂反应选择性和催化效率较低,显著限制了其实际应用。本文报道了在炭布基底表面生长氢氧化钴,随后再在其表面原位生长石墨炔(GDY/Co(OH)_(2))来可控制备高性能CER电催化剂的简单方法。在酸性模拟海水中,GDY/Co(OH)_(2)在10 mA cm^(-2)电流密度时的过电位仅为83 mV,最大法拉第效率(FE)为91.54%,氯产率高达157.11 mg h^(-1)cm^(-2)。实验结果表明,GDY在Co(OH)_(2)表面原位生长形成了GDY与金属Co原子之间具有强电子转移的界面结构,从而获得更高的导电性、更大的活性比表面积和更多的活性位点,进而提高了整体电催化的选择性和效率。

Promoting effect and mechanism of neodymium on low-temperature selective catalytic reduction with NH3 over Mn/TiO2 catalysts

Series of Mn/TiO2 catalysts modified with various contents of Nd for low-temperature SCR were synthesized.It can be found that the appropriate amount of Nd can markedly reduce the take-off temperature of Mn/TiO2 catalyst to 80℃and NOx conversion is stabilized over 90%in the wide temperature range of 100-2600 C.0.1 Nd-Mn/Ti shows higher N2 selectivity and better SO2 resistance than Mn/Ti catalyst.The results reveal that Nd-doped Mn/TiO2 catalyst exhibits larger BET surface area and better dispersion of active component Mn2O3.XPS results indicate that the optimal 0.1 Nd-Mn/Ti sample possesses higher concentration of Mn4+and larger amount of adsorbed oxygen at the surface compared with the unmodified counterpart.In situ DRIFTS show that the surface acidity is evidently increased after adding Nd,especially,the Lewis acid sites,and the intermediate(-NH2)is more stable.The reaction mechanism over Mn/Ti and 0.1 Nd-Mn/Ti catalysts obey the Eley-Rideal(E-R)mechanisms under low temperature reaction conditions.H2-TPR results show that Nd-Mn/TiO2 catalyst exhibits better lowtemperature redox properties.

N-doped graphene and TiO_2 supported manganese and cerium oxides on low-temperature selective catalytic reduction of NO_x with NH_3

A series of N-doped graphene(NG)and TiO_2 supported MnO_x–CeO_2 catalysts were prepared prepared by a hydrothermal method.The catalysts with different molar ratios of Mn/Ce(6:1,10:1,15:1)were investigated for the low-temperature selective catalytic reduction(SCR)of NO_x with NH_3.The synthesized catalysts were characterized by HRTEM,SEM,XRD,BET,XPS,and NH_3-TPD technologies.The characterization results indicated that manganese and cerium oxide particles dispersed on the surface of the TiO_2–NG support uniformly,and that manganese and cerium oxides existed in different valences on the surface of the TiO_2–NG support.At Mn element loading of 8 wt%,MnO_x–CeO_2(10:1)/TiO_2–1%NG displayed superior activity and improved SO_(2 )resistance.On the basis of the catalyst characterization,excellent catalytic performance and SO_2 tolerance at low temperature were attributed to the high content of manganese with high oxidation valence,extensive oxidation of NO into NO_2 by CeO_2 and strong NO adsorption capacity,and electron transfer of N-doped graphene.

均相催化对氯甲苯合成2,4-二氯甲苯与3,4-二氯甲苯

以对氯甲苯为原料,金属氯化物为催化剂,一步法催化氯化制备2,4-二氯甲苯和3,4-二氯甲苯。考察催化剂种类、用量、反应时间、反应温度、氯气流量等条件对对氯甲苯转化率、2,4-二氯甲苯和3,4-二氯甲苯选择性的影响。结果表明:以四氯化锆为催化剂,催化剂含量3%,反应温度为30℃,反应时间控制在3 h内,对氯甲苯转化率为53.29%,2,4-二氯甲苯的选择性80.93%;以三氯化铝为催化剂,硫化亚铁为助催化剂,三氯化铝与硫化亚铁用量分别为0.3%与0.1%,反应温度为40℃,反应时间控制在3 h内,对氯甲苯转化率为33.35%,3,4-二氯甲苯的选择性为40.48%。对氯甲苯一步氯化法步骤简单、条件温和,产品二氯甲苯选择性灵活可控,为2,4-二氯甲苯与3,4-二氯甲苯合成工艺提供了一条切实可行的路线。

Dual single-atom Ce-Ti/MnO_(2)catalyst enhances low-temperature NH_(3)-SCR performance with high H_(2)O and SO_(2)resistance

Mn-based catalysts have exhibited promising performance in low-temperature selective catalytic reduction of NOx with NH_(3)(NH_(3)-SCR).However,challenges such as H_(2)O-or SO_(2)-induced poisoning to these catalysts still remain.Herein,we report an efficient strategy to prepare the dual single-atom Ce-Ti/MnO_(2)catalyst via ball-milling and calcination processes to address these issues.Ce-Ti/MnO_(2)showed better catalytic performance with a higher NO conversion and enhanced H_(2)O-and SO_(2)-resistance at a lowtemperature window(100−150°C)than the MnO_(2),single-atom Ce/MnO_(2),and Ti/MnO_(2)catalysts.The in situ infrared Fourier transform spectroscopy analysis confirmed there is no competitive adsorption between NOx and H_(2)O over the Ce-Ti/MnO_(2)catalyst.The calculation results showed that the synergistic interaction of the neighboring Ce-Ti dual atoms as sacrificial sites weakens the ability of the active Mn sites for binding SO_(2)and H_(2)O but enhances their binding to NH_(3).The insight obtained in this work deepens the understanding of catalysis for NH_(3)-SCR.The synthesis strategy developed in this work is easily scaled up to commercialization and applicable to preparing other MnO_(2)-based single-atom catalysts.

Switching of CO_(2)hydrogenation selectivity via chlorine poisoning over Ru/TiO_(2)catalyst

It is fascinating to explore the distribution of CO_(2)hydrogenation products regulated by heterogeneous catalysts,as both the chemical state of surface metals and structure of the support itself of the supported catalysts may affect the performance of CO_(2)hydrogenation.Herein,the complete switching of CO_(2)hydrogenation products from CH4 to CO can be realized by induction of Cl into Ru/TiO_(2)catalyst.Density functional theory(DFT)calculations indicated that Cl ions were mainly located on the Ru metal sites of Ru/TiO_(2)catalysts.Bader charge analysis and Ru 3p X-ray photoelectron spectra(XPS)results suggested that electrons transferred from Ru to Cl,resulting in the decrease of electron density of Ru.In situ diffuse reflectance infrared Fourier transform spectroscopy(DRIFTS)of CO_(2)hydrogenation and CO adsorption proved that with the increase of the Cl ion content,the adsorption of CO on the catalyst surface was significantly weakened,and resulted in the high CO selectivity.Our work demonstrates the role of Cl ions in regulating the distribution of CO_(2)hydrogenation products,and provides new ideas for regulating other catalytic processes.

事故氯处理装置的复核

以25万t/a烧碱的某企业电解车间所配套的事故氯处理装置为例,复核该事故氯处理装置关键设备的选型设计,发现问题并提供解决方案。

铜精矿中氟氯的连续测定

采用过氧化钠碱熔融,用沸水浸出熔融物后干过滤,准确分取一份滤液于pH6.5~7.0的柠檬酸钠-三乙醇胺介质中,用高精度离子计测定试液中氟离子浓度,从而得出试样中氟含量。再准确分取另一份滤液,于乙醇-水溶液中用硝酸银标准溶液电位滴定测定试液中的氯量。方法用于分析铜精矿中氟氯连续测定。氟离子和氯离子的加标回收率在98.83%~101.05%,99.65%~100.62%之间,相对标准偏差(RSD,n=7)0.065%~1.5%,0.102%~0.890%之间。

氯碱生产中常见腐蚀及防护

介绍了氯碱生产中主要的腐蚀介质,提出设备及管道的选材防腐对策。

离心式氯气压缩机在氯碱行业中的应用及选型

介绍了离心式氯气压缩机在氯碱行业中的应用;随着近年来单条线烧碱装置规模的不断扩大,对机组选型应考虑的主要因素进行了相关说明,以此作为今后类似机组选型设计的借鉴和参考。

硒在单氯代二甲苯合成反应中高选择性作用的研究

本文利用本公司的发明专利技术“一种使用元素硒作为催化剂生产对氯甲苯的方法”,将其扩展延伸应用至邻二甲苯、间二甲苯的氯化反应生产单氯代二甲苯的氯化反应中,并对其氯化反应条件、转化率、选择性、套用效果等进行研究。发现元素硒同样对邻二甲苯或对二甲苯的氯化反应选择性和转化率有显著的改善作用,能提高4-氯邻二甲苯和4-氯间二甲苯的选择性,并有效抑制二氯代化合物的产生,具有较好的工业化应用价值和推广应用研究价值。