自拟合纳米二氧化钛催化污水处理剂的研究与开发

利用硫酸法钛白粉副产稀硫酸与钛原料生产硫酸钛溶液,再与碱性印染污水中和,自拟合生成超细纳米二氧化钛颗粒,催化氧化分解污水中的有机物,减少现有芬顿法过氧化氢的用量70%。采用紫外光催化氧化,全部替代过氧化氢的用量,污水中的化学需氧量（COD）去除率提高14.5%,达到94.5%。开发了钛白粉生产废硫酸作为印染污水处理的经济方法,耦合了2个相关行业“冗余”的化学资源和化学能源,做到了低成本、经济的纳米二氧化钛催化剂的生产合成,降低了印染污水处理的生产费用,效果显著。     

Microbial removal of sulfur dioxide from a gas stream

A study of the feasibility of utilizing the Thiobacillus ferrooxidans or Desulfovibrio desulfuricans bacterium for microbial removal of sulfur dioxide from flue gases has been carried out. Sulfur dioxide may be readily reduced to H₂S by contact with sulfate-reducing microorganisms in which Desulfovibrio desulfuricans were dominant in the first stage. The H₂S was then oxidized to sulfur by the ferric sulfate in a second stage where ferrous ions were regenerated. These results were compared to microbial oxidation of SO₂ from flue gases to sulfate by Thiobacillus ferrooxidans. The mechanisms for the reduction of SO₂ to H₂S in the presence of Desulfovibrio desulfuricans and the oxidation of SO₂ to H₂SO₄ in the presence of ferric sulfate and Thiobacillus ferrooxidans are discussed. Sulfuric acid or gypsum CaSO₄ · 2H₂O are byproducts from microbial flue gas desulfurization.     

臭氧催化氧化降解煤化工高盐废水有机物的机理

研究了臭氧催化氧化降解煤化工高盐废水有机物的机理。实验采集了国内典型煤化工企业高盐废水,明确了水中盐离子的组成及含量;制备高盐性臭氧催化剂,研究了不同活性组分对臭氧催化氧化效率的影响,确定了最佳的臭氧催化剂;对臭氧催化剂开展表征分析,明确催化剂表观形貌、元素组成及负载情况;最后采用甲酸模拟水样,研究臭氧催化氧化作用方式、臭氧衰减率变化、羟基自由基（·OH）变化、H₂O₂变化及超氧自由基（·O₂^-）变化,明确臭氧催化氧化作用机理及反应历程。结果表明：煤化工高盐废水阳离子主要为钠离子,其次是钾离子、钙离子、镁离子;阴离子主要为氯离子、硫酸根,其次是硝酸根离子;通过研究不同活性组分对臭氧催化氧化效率确定最佳催化剂为SiO₂/Al₂O₃-Fe₂O₃。对催化剂开展表征分析发现：催化剂载体为硅铝复合氧化物,铁作为活性组分均匀负载于载体上。臭氧催化氧化降解机理研究发现：臭氧催化氧化过程遵从羟基自由基作用机理,O₃通过衰减产生羟基自由基,而催化剂的加入促进了·OH生成;反应过程中产生的H₂O₂量与·?OH有关,·?OH越多,H₂O₂产生量越多,但·O₂^-的产生与·OH没关系。     

(NH4)2S吸收净化冶炼烟气中SO2回收硫资源的方法

采用(NH₄)₂S溶液吸收净化高浓度SO₂烟气,得到(NH₄)₂S₂O₃和NH₄HSO₃的混合溶液并转移至高压反应釜中,控制反应条件,两种物质发生自氧化还原反应,生成硫磺和(NH₄)₂SO₄.实验考察了吸收SO₂过程和自氧化还原过程的影响条件,结果表明:在pH=3～7,SO₂气体流速300 ml·min^-1,(NH₄)₂S浓度为0.2～1.2 mol·L^-1,常温条件下,烟气中二氧化硫的吸收率达到99.8%以上,且无H₂S生成;在pH=2.5～3.0,温度为130℃条件下,反应进行1 h,硫磺收率达到95%以上,溶液经过蒸发结晶得到(NH₄)₂SO₄.用X射线衍射(XRD)和X射线荧光光谱(XRF)对硫磺和硫酸铵进行表征分析,结果表明:硫磺的纯度为99.14%,硫酸铵中氮元素含量为23.6%.     

工业制SO3气体浓度实时检测及多元非线性回归建模

工业接触法制SO₃气体浓度高、腐蚀性强、交叉影响大，高精度实时检测困难，且原料流量与SO₃浓度的关系尚不明确，参数调节依赖经验。针对上述问题，采用AO2电化学氧传感器设计了一种工业制SO₃气体浓度的实时检测系统，并构建了输入空气、SO₂流量与输出SO₃浓度的多元非线性回归模型。SO₃气体浓度实时检测系统主要包括AO2电化学氧传感器、传感器调理电路、AD620放大电路及ADS1256 A/D转换电路，通过检测SO₃发生装置输入空气与输出混合气体中O₂浓度的毫伏级变化，间接测量SO₃浓度，避免了其他敏感气体的交叉影响，实验结果表明检测系统的检测时间为27s，灵敏度为111mV/%，偏差小于0.18%，稳定性良好，证明了检测系统的有效性；利用响应面法建立了预测SO₃浓度的三次多项式非线性回归模型，对该模型进行方差分析后结果显著，测试后均方误差（MSE）为0.0007174，相关系数（R²）为0.9929，拟合度好、预测精度高。     

CeO2表面氧化转移FCC烟气中SO2的反应过程

为提高Ce基脱硫助剂对石油加工过程中流化催化裂化（FCC）烟气深度脱硫效果,采用实验与密度泛函理论（DFT）探究了SO₂、O₂在CeO₂表面的反应过程。通过60℃、200℃反应温度下SO₂、O₂与CeO₂的反应,对反应前后CeO₂样品的XRD、IR、XPS谱图比较分析,探索S、Ce的价态变化和相对含量转变规律,从而推测SO₂可能的反应路径。基于密度泛函理论模拟构造了O₂单分子和SO₂、O₂双分子在CeO₂（111）和MgAl₂O₄（111）O空位表面可能产生的吸附构型;利用LST/QST方法搜索SO₂氧化反应过程,计算各步反应能垒。结果表明CeO₂（111）相比MgAl₂O₄（111）具有更好的SO₂催化效果,其中CeO₂在反应中起到了晶格O传递作用,并进一步推断SO₃的脱附过程是整个反应的速率控制步骤。     

Effect of V2O5 on the catalytic activity of Pt-based diesel oxidation catalyst

We investigated the suppression of SO₂ oxidation activity by vanadium oxide in Pt-based diesel oxidation catalyst using reaction experiments, temperature programmed desorption (TPD), infrared (IR) and X-ray photoelectron spectroscopy (XPS). There was no interaction between Pt and S indicated by the XPS results. SO₂ was not adsorbed on Pt at room temperature indicated by the absence of peak arising from SO₂ in SO₂ TPD spectra. SO₂ molecules were adsorbed on the hydroxyl groups of TiO₂ and migrated to Pt particles to react with oxygen adsorbed on it. V₂O₅ decreased the adsorption of SO₂ on TiO₂ by the blockage of V₂O₅ on TiO₂.     

An infrared study of the behavior of SO2 and NOx over carbon and carbon-supported catalysts

The heterogeneous reactivity of NO_x and SO₂ with carbon has been investigated with FT-IR spectroscopy. The interaction between NO and SO₂ on carbon surface have been studied in the presence and in the absence of oxygen. Thermal stabilities of surface structures, formed as a result of NO_x and SO₂ chemisorption have been determined by means of FT-IR spectroscopy. During the reaction of NO/O₂ mixture with carbon the surface species, including C–NO₂, C–ONO, C–NCO and anhydride structures are formed. It has been found that SO₂ retards the oxidation reaction of carbon by oxygen. The oxidation of SO₂ on carbon was found to be greatly enhanced by the presence of NO + O₂ mixture. The adsorption capacity of cellulose based carbon, catalytic NO_x decomposition and TPD was studied using a fixed bed flow reactor.     

Denitrification performance and sulfur resistance mechanism of Sm–Mn catalyst for low temperature NH3-SCR

MnO_x and Sm–Mn catalysts were prepared with the coprecipitation method, and they showed excellent activities and sulfur resistances for the selective catalytic reduction of NO_x by NH₃ between 50 and 300 °C in the presence of excess oxygen. 0.10Sm–Mn catalyst indicated better catalytic activity and sulfur resistance. Additionally, the Sm doping led to multi-aspect impacts on the phases, morphology structures, gas adsorption, reactions process, and specific surface areas. Therefore, it significantly enhances the NO conversion, N₂ selectivity, and sulfur resistance. Based on various experimental characterization results, the reaction mechanism of catalysts and the effect of SO₂ on the reaction process about the catalysts were extensively explored. For 0.10Sm–Mn catalyst, manganese sulfate and sulfur ammonium cannot be generated broadly under the influence of SO₂ and the amount of surface adsorbed oxygen. The Bronsted acid sites strengthen significantly due to the addition of SO₂, enhancing the sulfur resistance of the 0.10Sm–Mn catalyst.     

原位拉曼和红外技术对二氧化铈脱硝催化剂硫酸化处理过程的研究

NH_3选择性催化还原NOx技术的关键是催化剂,其中,理解催化剂的硫中毒机制是获取抗硫中毒催化剂的有效方法。借助原位拉曼和红外表征考察氧化态、还原态CeO_2催化剂在二氧化硫、氧气处理气氛中体相和表面硫酸盐以及氧缺陷的变化。NH_3-SCR催化反应结果表明,硫酸化还原态CeO_2具有较优的脱硝性能,这主要来源于还原态CeO_2上的缺陷,有利于氧化SO_2,产生表面硫酸盐,增强催化剂酸性,同时抑制体相硫酸盐的生成,促进NH_3-SCR反应的进行。     

Manganese leaching in high concentration flue gas desulfurization process with semi-oxidized manganese ore

Manganese leaching during high concentration flue gas desulfurization process with semi-oxidized manganese ore was studied in this paper. It was found that there were different reaction pathways among which MnO_2,Mn_2O_3 and MnCO_3 in semi-oxidized manganese ore during flue gas desulphurization and manganese leaching.High SO_2 concentration facilitated redox reaction between MnO_2 and SO_2, and high concentration of H_2SO_4 accelerated MnCO_3/Mn_2O_3 leaching from semi-oxidized ore. Kinetics study showed that manganese leaching in flue gas desulfurization process with semi-oxidized ore was controlled by a mixed-control model, that is the surface chemical reaction and mass diffusion dominated both the oxidation of SO_2 and manganese leaching process. The apparent activation energy was 13.05 k J·mol~(-1) and the reaction orders with respect to SO_2 and H_2SO_4 concentration were 1.38 and 0.10, respectively. Finally, a semi-empirical rate equation based on shrinking core model was derived to describe the process.     

三聚氰胺与SO2反应及再生行为

以固体有机胺三聚氰胺（MN）为脱硫剂,对MN与SO₂反应及再生行为进行研究。结果表明,烟气组成0.35% SO₂+5% O₂+N₂,40℃、4% MN（质量分数）条件下,MN可维持140 min脱硫率>99%,穿透硫容（出口SO₂浓度200 mg/m³）0.33 g SO₂/（g MN）。MN脱硫及再生产物XRD、FTIR、SEM及TG-MS等表征分析表明,MN与SO₂反应首先生成三聚氰胺亚硫酸盐,随后被烟气中的氧气氧化为三聚氰胺硫酸盐,加入0.1%对苯二胺可有效抑制三聚氰胺亚硫酸盐氧化;三聚氰胺亚硫酸盐在75~150℃可加热再生,三聚氰胺硫酸盐不能加热再生。烟气含5% O₂条件下,加入0.1%对苯二胺,三聚氰胺亚硫酸盐氧化率由36%降低至13%,150℃下再生2 h,再生率由58%提高至94%,MN抗氧二次脱硫性能优良。     

2,3-吡啶二羧酸合成尾气吸收实验研究

2,3-吡啶二羧酸合成产生的尾气中含有氯气,必须完全除去氯气,尾气才可达标排放。采用亚硫酸钠溶液和氢氧化钠溶液作为尾气吸收液进行对照实验,并考察了影响尾气吸收效果的因素。实验结果表明,亚硫酸钠吸收氯气效果优于氢氧化钠,适当降低流速以及提高吸收液浓度有利于吸收氯气。用30%氢氧化钠溶液调节吸收液pH可最大程度发挥亚硫酸钠吸收氯气的能力,每50 g喹啉反应对应需要300 g 20%亚硫酸钠和500 g 30%氢氧化钠吸收尾气中的氯气。整个反应中尾气未检测到氯气及二氧化硫等有害气体,吸收效果较好。     

Catalytic NO reduction with ammonia at low temperatures on V2O5/AC catalysts: effect of metal oxides addition and SO2

The catalytic behavior of the V-M/AC (M=W, Mo, Zr, and Sn) catalysts were studied for the NO reduction with ammonia at low temperatures, especially in the presence of SO₂. The presence of the metal oxides does not increase the V₂O₅/AC activity but decreases it. Except V-Mo/AC, the other catalysts are promoted by SO₂ at 250°C, especially for V-Sn/AC. However, the promoting effect of SO₂ is gradually depressed by catalyst deactivation. Changes in catalyst preparation method can improve the catalyst stability in short-term but cannot completely prevent the catalyst from a long-term deactivation. Mechanisms of the promoting effect and the deactivation of V-Sn/AC catalyst by SO₂ were studied using Fourier transform infrared spectroscopy (FT-IR) spectra and measurement of catalyst surface area and pore volume. The results showed that both the SO₂ promotion and deactivation are associated with the formation of sulfate species on the catalyst surface. In the initial period of the selective catalytic reduction (SCR) reaction in the presence of SO₂, the formed sulfate species provide new acid sites to enhance ammonia adsorption and thus the catalytic activity. However, as the SCR reaction proceeds, excess amount of sulfate species and then ammonium-sulfate salts are formed which is stabilized by the presence of tin oxide, resulting in gradual plugging of the pore structures and the catalyst deactivation.     

不同气氛对硫铁矿和硫酸亚铁反应的影响研究

研究了硫铁矿分解硫酸亚铁的固-固反应,通过HSC热力学软件模拟和实际实验研究考察了含二氧化硫气氛和含氧气氛对硫铁矿分解硫酸亚铁的影响。热力学研究结果表明,二氧化硫对反应无明显影响,氧会增加硫酸亚铁的完全分解温度。实验研究表明,二氧化硫会降低原料脱硫率,但进一步增大二氧化硫浓度不会进一步影响原料脱硫率,这与热力学研究结果有差异,是因为HSC软件未考虑反应平衡;氧气浓度越高,原料脱硫率越低,主要因为氧气消耗掉部分还原剂硫铁矿。     

Activation of monolithic catalysts based on diatomaceous earth for sulfur dioxide oxidation

The formation of the active phases during the activation process of monolithic catalysts based on V₂O₅–K₂SO₄ supported on diatomaceous earth for SO₂ to SO₃ oxidation in flue gases, has been shown to be a crucial factor to achieve satisfactory catalytic performance. As the temperature is increased from room temperature to 470°C, SO₂ and SO₃ are taken up by the green catalyst and the precursors are transformed into the active species. The role of each component of the catalyst during the activation was analyzed by studying the behavior towards SO₂ adsorption of four materials, which contained: diatomaceous earth, diatomaceous earth + V, diatomaceous earth + K, and diatomaceous earth + V + K. The influence of the potassium sulfate accessibility in the green catalyst was studied by using two different preparation methods, which gave rise to differences in the catalysts SO₂ adsorption properties and catalytic performance. Furthermore, the influence of the activation atmosphere was studied using nitrogen, oxygen or a flue gas composition. It was shown that pyrosulfate species should be formed at temperatures below 400°C, to keep the vanadium in the active 5+ oxidation state.     

MIXED COBALT-BASED CATALYSTS IN AUTOXIDATION OF AQUEOUS SO2

The kinetics of aqueous sulphur dioxide autoxidation catalyzed simultaneously by ions of two different transition metals was studied. Basing on the mechanism of a chain reaction the rate equation for oxygen consumption has been derived. Interaction of the ions in redox steps was assumed. The equation was tested against experimental data collected during oxygen absorption performed in a gas-liquid reactor with a plane interface. Two catalytic systems were used in the experiments: CoSO₄-Fe₂(SO₄)₃ and CoSO₄-MnSO₄

The predicted occurrence of a minimum value of oxygen absorption rate at a certain concentration ratio of metal ions constituting a mixed catalyst was confirmed for both systems. Other phenomena related to the possible removal of a catalyst or sulphite from the place of reaction were also discussed.     

Modifications to the surface chemistry of low-rank coal-based carbon catalysts to improve flue gas nitric oxide removal

The effectiveness of carbons as low-temperature selective catalytic reduction (SCR) catalysts will depend upon their physical and chemical properties. Surface functional groups containing oxygen are closely related to the catalytic activity of carbons. These groups are expected to change the interaction between the carbon surface and the reactants through a variation in adsorption and reaction characteristics. This paper presents a more detailed study of the effects of either gas-phase sulfuric acid or oxygen oxidation treatments on the catalytic NO reduction by low-rank coal-based carbon catalysts. Raw and treated carbons were characterized by N₂ and CO₂ surface areas, TPD and ash content. NO removal capacity of carbons was determined by passing a flow containing NO, H₂O, O₂, NH₃ and N₂ through a fixed bed of carbon at 150°C and 4 s of residence time, the effluent concentration being monitored continuously during the reaction. The effects of varying the type and conditions of the treatment on the physicochemical features of carbons were studied. The gas-phase sulfuric acid treatment (corresponding to a first step SO₂ removal) markedly enhanced carbon activities for NO removal. On the contrary, oxygen oxidation enhanced NO removal capacity of chars to a lower extent. Therefore, the carbons studied could be used in a combined SO₂/NO removal process, because the use and regeneration of the carbon in the first step is beneficial for the performance in the second one.     

臭氧多脱副产物亚硝酸钙的复盐沉淀试验研究

针对复盐沉淀法(氢氧化钙与亚硝酸钙反应生成复盐沉淀)处理烟气中臭氧氧化氮氧化物的液相吸收产物亚硝酸钙,采用控制变量法对此反应的诸多影响因素(反应温度、反应物浓度、反应过程扰动和反应物形态等)进行了试验研究.结果表明:为提高复盐沉淀效率,需要选择合适的反应温度(80℃最佳),同时反应物投药量的增加以及反应过程湍流度的增大都能够有效提高复盐共沉淀效率.复盐沉淀会伴随着氢氧化钙的析出而动态产生,构建氢氧化钙的析出条件能提高亚硝酸钙捕集效率.     

Catalytic decomposition of methylene chloride by sulfated oxide catalysts

Catalytic decomposition of methylene chloride in air with a concentration of 959 ppm and temperature ranges from 160 to 275°C were studied. Three different sulfated oxide catalysts, TiO₂(SO₄), ZrO₂(SO₄), CeO₂(SO₄) were prepared and their activities and selectivities were measured. The catalytic activity decreased in the order: TiO₂(SO₄) > ZrO₂(SO₄) > CeO₂(SO₄). Complete catalytic decomposition of methylene chloride was achieved at low temperature (275°C) over a sulfated titanium dioxide catalyst. The oxygen adsorption (pick-up) and the acidity values of three catalysts showed the same trend as their activities. The presence of water (2% in volume) in the feed stream reduced the activities remarkably and raised the activation energies for the decomposition reaction. The selectivities among all three catalysts were similar, with HCl, CO and CO₂ being the products. A bifunctional catalyst comprising sulfated titanium dioxide with copper oxide was developed to improve the selectivity of catalytic oxidation of methylene chloride towards carbon dioxide.