煅烧温度对Mo-Mn/TiO2催化剂脱硝脱汞活性的影响

研究了浸渍法制备Mo-Mn/TiO₂（MMT）催化剂过程中煅烧温度（300℃、450℃、600℃、750℃）对Mo-Mn/TiO₂（MMT）催化剂协同脱硝脱汞活性的影响。结果表明,较低的煅烧温度更有利于MMT催化剂的协同脱硝脱汞性能,同时可有效降低SO₂对催化剂活性的抑制作用,最佳煅烧温度为300℃。利用BET、XRD、H₂-TPR、FTIR和XPS等表征手段对催化剂的理化性质进行了表征,结果表明较低的煅烧温度有利于提高催化剂中活性成分所占的比例,增加金属氧化物在TiO₂载体表面的分散度,提高催化剂的低温还原性能。随着煅烧温度的升高,催化剂的比表面积和孔容均逐渐减小,平均孔径先增大后减小,且在高温下发生烧结;MnO₂逐渐向Mn₂O₃转变,锐钛矿型TiO₂逐渐向金红石型转变,同时MoO₃由非晶态逐渐向晶态的转化,致使催化剂的协同脱硝脱汞活性下降。     

耦合传质的羰基化固定床反应器传热模拟分析

固定床反应器中进行强放热反应时, 反应器的热点温度对操作参数变化敏感,容易引起飞温,导致转化率下降,影响催化剂寿命。为强化羰基化固定床反应器内热质传递与化学反应的协同性,建立考虑颗粒内扩散影响的羰基化固定床反应器拟均相一维传热模型,考察操作参数对床层热点温度、反应转化率、床层温升的影响。不仅体现传热传质和反应的协同作用,而且影响关系明晰、求解方便。为保证反应转化率,本实验条件下确定催化剂颗粒直径小于等于1.5 mm。反应器入口温度/冷却剂油温既要满足床层热稳定性需求,又要使反应转化率和床层温升都在合理范围内。模拟结果表明在床层入口温度升高的同时,可通过降低冷却剂油温获得良好的反应转化率和较小的床层温升。在此基础上,考察入口环氧乙烷浓度对反应转化率和床层温升的影响。本研究可为固定床反应器满足转化率要求、床层合理温升而选择催化剂颗粒直径、床层入口温度、冷却剂油温和床层入口浓度等操作参数提供计算依据。     

A predictive neural network model based on the karhunen-loéave expansion for wall-cooled fixed-bed reactors

Experiments were carried out with a pilot scale, wall cooled, fixed-bed reactor for benzen oxidation. The inlet concentration of benzene was varied in three ways: periodically, with PRBS, and by means of a step change. A model for the reactor is developed with use of the Karhunen-Loéve (K-L) expansion and neural networks. The K-L expansion procedure used here acts as a preprocessor to achieve good data compression while preserving as much information about the measurements as possible. A recurrent multilayer feedforward network is then used to relate the coefficients of the K-L expansion to the operating conditions. The model developed is used for on-line prediction of the axial temperatures in a fixed-bed reactor and results show that the predictions are in good agreement with measurements.     

Ni-CeO2-K/γ-Al2O3催化剂上沼气联合重整制合成气

采用超声波辅助等体积浸渍法制备Ni-CeO₂-K/γ-Al₂O₃催化剂用于沼气联合重整反应,采用 BET、XRD、TG/DTG等技术对催化剂性质进行了表征,在微型固定床反应装置中研究了反应温度、体积空速、原料气组成等对沼气联合重整反应特性的影响,并对催化剂的稳定性进行了研究。结果表明,助剂CeO₂的加入,提高了催化剂中Ni的分散度,降低了催化剂还原温度。升高反应温度和减小体积空速,能够提高沼气中CH₄和CO₂的转化率;原料气中加入水蒸气,能够明显提高H₂/CO体积比;加入的O₂容易与H₂、CO发生反应,CH₄转化率稍有提高。在常压、反应温度850℃、体积空速为100000h^-1、摩尔比CH₄∶CO₂∶H₂O∶O₂∶Ar=1∶0.5∶0.5∶0.1∶0.01的优化条件下,沼气中CH₄转化率超过95%,CO₂转化率超过75%,生成合成气H₂/CO体积比约为1.6,反应48h后,催化剂未见积炭,保持稳定的活性。与沼气干重整相比,沼气联合重整不利于沼气中CO₂的转化。     

Catalytic Ozonation by Manganese,Iron and Cerium Oxides on γ-Al2O3 Pellets for the Degradation of Organic Pollutants in Continuous Fixed-Bed Reactor

ABSTRACT

Heterogeneous catalytic ozonation is an efficient technology for degrading refractory organic pollutants in water. However, most studied heterogeneous catalysts for catalytic ozonation were powders, which were not practically available for continuous fixed-bed reactor in water treatment. In this work, manganese, iron and cerium oxides on γ-Al₂O₃ pellets were synthesized and used as heterogeneous catalysts for catalytic ozonation in a continuous fixed-bed reactor. Results showed that all the prepared metal oxides on γ-Al₂O₃ pellets exhibited facilitated catalytic ozonation for degrading refractory contaminates compared with ozonation alone and catalytic ozonation on pure γ-Al₂O₃ pellets. The cerium oxides supported on γ-Al₂O₃ pellets (CeO₂/γ-Al₂O₃) performed best catalytic performance with the COD removal efficiency of 64.3% and TOC removal efficiency of 41.7%. Moreover, the catalytic activity was further enhanced by the synergistic effect of the bimetallic oxides on γ-Al₂O₃ pellets (CeO₂-Fe₂O₃/γ-Al₂O₃). This study is expected to help to encourage further research and applications in AOPs based on the success of this work in designing heterogeneous catalysts available for continuous fixed-bed reactor.     

碳材料吸附脱除二氧化硫性能的影响因素

选用了7种不同物理化学特性的碳材料,分别为活性炭-1 (比表面积1779m²/g)、活性炭-2 (比表面积970m²/g)、多孔纳米炭-1 (平均孔径14nm)、多孔纳米炭-2 (平均孔径85nm)、多孔纳米炭-3 (平均孔径4.7nm,掺氮)、多孔纳米炭-4 (平均孔径4.1nm,不掺氮)和纳米碳纤维。在对比这7种不同的碳材料的物理化学特性与其脱硫性能的基础上,研究材料的物理化学特性、脱硫温度、反应空速等因素对碳材料吸附脱除SO₂性能的影响。结果表明,碳材料吸附脱除SO₂的性能受材料的比表面积、孔隙结构、表面官能团、脱硫温度和反应空速的综合影响。不同的碳材料中,材料的孔隙结构和表面官能团对材料的脱硫性能影响很大,以微孔结构为主的碳材料SO₂去除率较高,以介孔结构为主的碳材料脱硫容量较高;随着脱硫温度升高,碳材料的吸附脱硫性能降低;随着反应空速降低,碳材料的吸附脱硫性能升高。本研究中,多孔纳米炭NCP-10的吸附脱除SO₂性能最好,能在室温下保持100%的...     

ESP飞灰和FF飞灰脱汞特性的试验研究

采用汞渗透管产生的汞蒸气和其它主要烟气成分,在小型多功能固定床试验台上开展静电除尘器( ESP)飞灰和布袋除尘器(FF)飞灰脱除单质汞的试验研究.结果表明:O2、SO2、NO对Hg0的氧化均有一定的作用,尤其SO2对Hg0的氧化效果最为显著.飞灰对汞的吸附与飞灰中Fe2O3、Al2O3等化学成分的催化氧化有一定的相关性...     

Anaerobic degradation of nonionic and anionic surfactants in enrichment cultures and fixed-bed reactors

Anaerobic biodegradation and inhibitory effects of nonionic and anionic surfactants on methanogenic fermentation were tested in incubation experiments with anoxic sediment samples and sewage sludge. Alkylsulfonates and alkylbenzenesulfonates were not degraded but inhibited methanogenesis from sludge constituents at concentrations ≥10 mgl⁻¹. Sodium dodecylsulfate was at least partly degraded after adaptation at concentrations 100 mgl⁻¹ and the sulfate group was reduced to sulfide. The polyethyleneglycol moiety of alkylphenolethoxylates was fermented to methane at concentrations 500 mgl⁻¹ whereas the alkylphenol residue probably remained unchanged. Alkylethoxylates were completely degraded to methane and CO₂ at concentrations up to 1.0 gl⁻¹. Complete anaerobic degradation of this surfactant type to methane, CO₂, and traces of acetate and propionate was demonstrated in a lab scale anaerobic fixed-bed reactor, either with prereduced mineral salts medium or with air-saturated artificial wastewater. This process lends itself as a suited, inexpensive means for treatment of wastewaters containing enhanced loads of nonionic surfactants, e.g. from the surfactant manufacturing or processing industry.     

氧化性气氛下煤热解脱硫的实验研究

在氧化性气氛中采用固定床反应系统对合山原煤进行了热解脱硫效果考察。主要考察了热解温度、热解时间对煤中挥发分和硫变化的影响。结果发现:随热解温度的升高,挥发分的损失量增加,而半焦的含硫量呈现先是升高而后下降的变化趋势;随热解时间的延长,挥发分的损失量增加,而半焦的含硫量呈现先是下降而后升高的变化趋势。     

重力热管在固定床鼓泡反应器中传热性能的实验研究

通过实验,研究了重力热管在固定床鼓泡反应器中的传热性能。分析了热水流量、气体流量、冷却水流量对床层温度分布和热管传热功率的影响．