玄武岩催化甲烷裂解制 C2 烃

以天然玄武岩为甲烷裂解催化剂,通过XRF、XRD、SEM及XPS对催化剂组成、结构、表面活性物种进行了研究。利用固定床反应装置考察了不同反应温度、空速条件下玄武岩催化甲烷裂解制C_2烃的效果。结果表明,在气体空速为4 L·h-1条件下,当反应温度为1 225 K时,甲烷的转化率为7.66%,C_2烃的选择性为33.64%;当反应温度升至1 325 K时,甲烷的转化率可达17.13%,同时C_2烃的选择性为27.21%。相同温度下,气体空速越大,乙烷的选择性越高,乙炔的选择性越低。催化剂活性因表面积炭的产生而降低,积炭类型为芳烃积炭。     

Hydrogen production via catalytic steam reforming of fast pyrolysis bio-oil in a two-stage fixed bed reactor system

Hydrogen production was prepared via catalytic steam reforming of fast pyrolysis bio-oil in a two-stage fixed bed reactor system. Low-cost catalyst dolomite was chosen for the primary steam reforming of bio-oil in consideration of the unavoidable deactivation caused by direct contact of metal catalyst and bio-oil itself. Nickel-based catalyst Ni/MgO was used in the second stage to increase the purity and the yield of desirable gas product further. Influential parameters such as temperature, steam to carbon ratio (S/C, S/CH₄), and material space velocity (W_BHSV, GHSV) both for the first and the second reaction stages on gas product yield, carbon selectivity of gas product, CH₄ conversion as well as purity of desirable gas product were investigated. High temperature (> 850 °C) and high S/C (> 12) are necessary for efficient conversion of bio-oil to desirable gas product in the first steam reforming stage. Low W_BHSV favors the increase of any gas product yield at any selected temperature and the overall conversion of bio-oil to gas product increases accordingly. Nickel-based catalyst Ni/MgO is effective in purification stage and 100% conversion of CH₄ can be obtained under the conditions of S/CH₄ no less than 2 and temperature no less than 800 °C. Low GHSV favors the CH₄ conversion and the maximum CH₄ conversion 100%, desirable gas product purity 100%, and potential hydrogen yield 81.1% can be obtained at 800 °C provided that GHSV is no more than 3600 h^− 1. Carbon deposition behaviors in one-stage reactor prove that the steam reforming of crude bio-oil in a two-stage fixed bed reaction system is necessary and significant.     

Syngas methanation for substitute natural gas over Ni–Mg/Al2O3 catalyst in fixed and fluidized bed reactors

A comparative study was conducted for laboratory syngas methanation over a self-made Ni–Mg/Al₂O₃ catalyst to demonstrate the technical advantages of fluidized bed over fixed bed reactor. At different reaction temperatures, gas velocities and pressures, the CO conversion and selectivity to CH₄ in fluidized bed were shown to be higher than in fixed bed, and much closer to the thermodynamic equilibriums. The spent catalysts from fluidized bed methanation had distinctively low and easy-oxidizing deposited carbon in comparison with that from fixed bed. The results were attributed to the bigger effective catalytic surface, better heat and mass transfer in fluidized bed reactor.     

Characteristics of carbon dioxide hydrogenation in a fluidized bed reactor

Characteristics of CO₂ hydrogenation were investigated in a fluidized bed reactor (0.052 m IDxl.5 m in height). Coprecipitated Fe-Cu-K-Al catalyst (d_ρ=75–90 Μm) was used as a fluidized solid phase. It was found that the CO₂ conversion decreases but the CO selectivity increases, whereas the space-time-yield attains maximum values with increasing gas velocity. The CO₂ conversion has increased, but CO selectivity has decreased with increasing hydrogenation temperature, pressure or H₂/CO₂ ratio in the fluidized bed reactor. Also, the CO, conversion and olefin selectivity appeared to be higher in the fluidized bed reactor than those of the fixed bed reactor. Presented at the Int’l Symp. on Chem. Eng. (Cheju, Feb. 8–10, 2001), dedicated to Prof. H. S. Chun on the occasion of his retirement from Korea University     

流化床在甲烷临氧CO2重整反应中的作用研究

在流化床反应器中进行甲烷临氧CO₂重整制合成气反应。通过计算分析了催化剂颗粒在床层内的流化特性。对比实验表明,流化床反应器在催化剂活性、稳定性、自热过程以及催化剂积炭等方面均体现出比固定床反应器的优越性。在流化床反应器中进行的甲烷自热重整反应,甲烷的转化率接近热力学平衡值,床层温度梯度小于10 ℃, 反应20 h后,催化剂表面无积炭。     

流化床中甲烷芳构化过程

在石英流化床反应器中研究了无氧条件下甲烷直接催化转化制备芳烃的过程.发现催化剂的诱导期长短、甲烷的总转化率与温度、甲烷分压及甲烷空速相关.在973 K下,液体产品中苯的选择性与萘的选择性随着催化剂的失活呈现不同的变化趋势.所得主要技术指标（甲烷转化率、苯的收率与选择性等）与固定床微型反应器中的结果相近.还研究了催化剂上的积炭对甲烷转化率、催化剂失活的影响,为将来的进一步研究提供了基础.     

A novel particle/monolithic two-stage catalyst bed reactor and their catalytic performance for oxidative coupling of methane

A novel two-stage catalyst bed reactor was constructed comprising of the 5%Na₂WO₄-2%Mn/SiO₂ particle catalyst and the 5%Na₃PO₄-2%Mn/SiO₂/cordierite monolithic catalyst. The reaction performance of the oxidative coupling of methane (OCM) in the two-stage bed reactor system was evaluated. The effects of the bed height and operation mode, as well as the reaction parameters such as reaction temperature, CH₄/O₂ ratio and flowrate of feed gas on the catalytic performance were investigated. The results indicated that the two-stage bed reactor system exhibited a good performance for the OCM reaction when the feed gases were firstly passed through the particle catalyst bed and then to the monolithic catalyst bed. The CH₄ conversion of 32.6% and C₂ selectivity of 67.5% could be obtained with a particle catalyst bed height of 10 mm and a monolithic catalyst bed height of 50 mm in the two-stage bed reactor. Both of the CH₄ conversion and C₂ selectivity have been increased by 4.8% and 2.5%, respectively, as compared with the 5%Na₂WO₄-2%Mn/SiO₂ particle catalyst in a single-bed reactor and by 7.7% and 16.1%, respectively, as compared with the 5%Na₃PO₄-2%Mn/SiO₂/cordierite monolithic catalyst in a single-bed reactor. The catalytic performance of the OCM in the two-stage bed reactor system has been remarkably improved. The TPR results indicate the high temperature reduction oxygen species in the monolithic catalyst might be favorable to the formation of C₂ products.     

丙烷脱氢制丙烯催化剂烧焦过程的模型化

在丙烷脱氢制丙烯反应过程中,由于焦的沉积使催化剂活性不断降低,而且失活速度很快,催化剂需频繁烧焦再生。在研究了丙烷脱氢催化剂烧焦过程内外扩散影响的基础上,采用内扩散效率因子修正的均匀烧焦物理模型,建立了综合考虑内外扩散影响的绝热固定床非均相动态烧焦数学模型,用于指导反应器的设计和操作优化。通过对Cr₂O₃/Al₂O₃脱氢催化剂烧焦过程模拟,可更深入地认识烧焦过程的变化规律。     

丙烷脱氢固定床反应器的动态模拟与优化

在丙烷脱氢制丙烯反应过程中,由于焦的沉积使催化剂活性不断降低,而且失活速度很快。本文建立了径向绝热固定床反应器丙烷脱氢 失活过程的动态模型,在Pt-Sn催化剂动力学基础上对脱氢过程进行了模拟和分析。得到了不同时刻反应器内的压力、温度、催化剂活性等的分布情况以及转化率、选择性、收率等的变化规律,并在分析反应器入口温度、流量及压力对过程影响的基础上对反应的操作条件进行了优化。     

Four-lump kinetic model for fluid catalytic cracking process

In the fluid catalytic cracking reactor heavy gas oil is cracked into more valuable lighter hydrocarbon products. The reactor input is a mixture of hydrocarbons which makes the reaction kinetics very complicated due to the involved reactions. In this paper, a four-lump model is proposed to describe the process. This model is different from others mainly in that the deposition rate of coke on catalyst can be predicted from gas oil conversion and isolated from the C₁–C₄ gas yield. This is important since coke supplies heat required for endothermic reactions occurring in the reactor. By this model we can also conclude that the C1–C4 gas yield increases with increasing reactor temperature, while production of gasoline and coke decreases.     

Simulation of activity loss of fixed bed catalytic reactor of MTO conversion using percolation theory

In this investigation, a reactor model for prediction of the deactivation behavior of MTO's porous catalyst in a fixed bed reactor is developed. Effect of coking on molecular transport in the porous structure of SAPO-34 has been simulated using the percolation theory. Thermal effects of the reaction were considered in the model and the temperature profile of the gas stream in the reactor was predicted. The predicted loss in catalyst activity with time-on-stream was in very good agreement with the experimental data. The resulting coke deposition and gas temperature profiles along the length of reactor suggested a reaction front moving toward the outlet of the fixed bed reactor at the operating experimental conditions of 1 h⁻¹ and 723 K for methanol space velocity and inlet temperature, respectively. Effects of space time, coordination of Bethe network, and effective diffusivity of component in reaction mixture on the reactor performance are presented.     

A comparison of co-current and counter-current modes of operation for a novel hydrogen-permselective membrane dual-type FTS reactor in GTL technology

In this work, a comparison of co-current and counter-current modes of operation for a novel hydrogen-permselective membrane reactor for Fischer-Tropsch Synthesis (FTS) has been carried out. In both modes of operations, a system with two-catalyst bed instead of one single catalyst bed is developed for FTS reactions. In the first catalytic reactor, the synthesis gas is partly converted to products in a conventional water-cooled fixed-bed reactor, while in the second reactor which is a membrane fixed-bed reactor, the FTS reactions are completed and heat of reaction is used to preheat the feed synthesis gas to the first reactor. In the co-current mode, feed gas is entered into the tubes of the second reactor in the same direction with the reacting gas stream in shell side while in the counter-current mode the gas streams are in the opposite direction. Simulation results for both co-current and counter-current modes have been compared in terms of temperature, gasoline and CO₂ yields, H₂ and CO conversion, selectivity of components as well as permeation rate of hydrogen through the membrane. The results showed that the reactor in the co-current configuration operates with lower conversion and lower permeation rate of hydrogen, but it has more favorable profile of temperature. The counter-current mode of operation decreases undesired products such as CO₂ and CH₄ and also produces more gasoline.     

流化床甲烷化基础与应用最新进展

由于CO甲烷化的快速表面反应、强放热特性,相比固定床,采用小颗粒催化剂的流化床甲烷化技术在反应活性和催化剂稳定性方面具有明显的技术优势。从高耐磨催化剂、流化床反应器及其创新、短流程两段甲烷化技术构建及其验证等方面总结了流化床甲烷化技术开发的最新进展。优化催化剂前体制备方法、调变催化剂组成可获得具有较高骨架强度和均匀性的催化剂一次微粒,进而通过优化的喷雾造粒工艺和填充黏结剂,制备出具有可调变粒度分布、高强度和高球形度的流化床用粉末催化剂,但其黏结剂的添加明显影响催化剂的低温活性。通过改性如Al₂O₃和FCC催化剂的球形颗粒,进而负载活性组分,开发了制备高活性、磨损指数小于1.5的流化床甲烷化Ni基催化剂的另一种技术方法。实验室研究证实了流化床甲烷化反应速率极快,在分布板上数毫米处即可实现可能的最高转化率,且在转化率和催化剂稳定性方面明显优于固定床,不仅由于流态化催化剂床层温度均匀,而且催化剂在床层内不停循环,加快了颗粒表面的更新。增大空速和表观气速,流化床的催化剂床层膨胀,反应气体与催化剂颗粒表面间的有效接触面积增加,使得流化床甲烷化对空速和表观气速的可调范围大。操作在更高气速条件的输送床甲烷化避免了操作气速的上限限制,可大幅降低反应器尺寸,有效提高单位截面的原料气负荷能力。输送床甲烷化可采用高热导率的催化剂颗粒传递反应热,相对于气体移热效率高、能力大。流化床甲烷化已在生物废弃物利用和焦炉煤气甲烷化方面开展了侧线示范,形成了相对多段绝热固定床工艺更简单的短流程两段甲烷化新工艺。     

空速对焦化汽油产物分布的影响

以抚顺焦化汽油为原料,采用小型固定流化床为反应装置,考察了空速对产物分布、轻油产品族组成、干气组成和液化气组成影响规律,同时通过实验数据建立了空速与干气收率、液化气收率、焦炭收率、轻油收率和总收率的关系式。实验结果表明,随着空速的增加,焦炭、干气和液化气收率逐渐下降,轻油收率逐渐增加,芳烃含量缓慢下降,而饱和烃含量基本没有变化。     

HZSM-5催化剂上甲醇制丙烯反应条件的研究

以HZSM-5分子筛为催化剂,在固定床反应器中考察了反应温度和原料空速对甲醇制丙烯性能的影响。结果表明,随着反应温度的升高,乙烯和丙烯选择性均增加,但温度过高容易引起催化剂的失活;而随原料空速的增大,甲醇转化率、乙烯和丙烯的选择性均呈下降趋势。最佳的反应条件为反应温度为460°C,原料液时空速为1.4 kg(Methanol)/kg(cat.).h。对添加粘结剂与未添加粘结剂成型后的催化剂性能比较,表明添加粘结剂成型后,甲醇转化率和丙烯选择性有所下降。     

Catalytic conversion of palm oil to fuels and chemicals

The conversion of palm oil to hydrocarbons using a shape selective zeolite catalyst is reported in this work. Palm oil was passed over HZSM-5 catalyst in a fixed bed micro-reactor and the reactor was operated at atmospheric pressure, a temperature range of 360 to 420°C and weight hourly space velocity (WHSV) of 2 to 4 h^?1. The main objective was to study the effect of reaction temperature and oil space velocity on the conversion and selectivity of gasoline range hydrocarbons. The results show that 40 to 70wt% of the palm oil can be converted to aromatics and hydrocarbons in the gasoline, diesel and kerosene range, light gases, coke and water. The maximum gasoline range hydrocarbons yield of 40wt% of total product formed was obtained at 400°C and 2 h^?1 space velocity.     

CO2 reforming of CH4 in coke oven gas to syngas over coal char catalyst

The CO₂ reforming of methane (in coke oven gas) on the coal char catalyst was performed in a fixed bed reactor at temperatures between 800 and 1200 °C under normal pressure. The effects of the coal char catalyst pretreatment and the ratio of CO₂/CH₄ were studied. Experimental results showed that the coal char was an effective catalyst for production of syngas, and addition of CO₂ did not enhance the CH₄ reforming to H₂. It was also found that the product gas ratio of H₂/CO is strongly influenced by the feed ratio of CO₂/CH₄. The modified coal char catalyst was more active during the CO₂–CH₄ reforming than the coal char catalyst based on the catalyst volume, furthermore the modified catalyst exhibited high activity in CO₂–CH₄ reforming to syngas. The conversion of methane can be divided into two stages. In the first stage, the conversion of CH₄ gradually decreased. In the second stage, the conversion of methane maintained nearly constant. The conversion of CO₂ decreased slightly during the overall reactions in CO₂–CH₄ reforming. The coal char catalyst is a highly promising catalyst for the CO₂ reforming of methane to syngas.     

催化裂化轻汽油在ZSM-5分子筛催化剂上裂化反应的研究

以ZSM-5分子筛为催化剂，在小型固定床反应器上，进行了催化裂化轻汽油的裂化反应。考察了反应温度和空速对催化裂化轻汽油裂化反应气液相收率和产品分布的影响。实验结果表明，ZSM-5分子筛催化剂具有较强的裂化活性和氢转移活性。在保证裂化转化率的条件下，提高反应温度和空速可以抑制催化剂上氢转移反应的发生。以ZSM-5分子筛为催化剂上的催化裂化反应中，温度、空速是影响转化率和选择性的重要因素，因此可以通过改变温度、空速来提高目的产物的选择性。但是，单纯依靠改善反应条件，不能使目的产物的收率和选择性达到理想的程度，还必须对催化剂进行改性。ZSM-5分子筛催化剂上催化裂化反应的研究为ZSM-5分子筛催化剂的进一步改性，及ZSM-5分子筛催化剂在轻汽油催化裂解和汽油改质方面的进一步应用提供了试验依据。     

Steam gasification of an australian bituminous coal in a fluidized bed

To produce low calorific value gas, Australian coal has been gasified with air and steam in a fluidized bed reactor (0.1 m-I.Dx1.6 m-high) at atmospheric pressure. The effects of fluidizing gas velocity (2–5 U_f/U_mf), reaction temperature (750–900 °C), air/coal ratio (1.6-3.2), and steam/coal ratio (0.63–1.26) on gas composition, gas yield, gas calorific value of the product gas and carbon conversion have been determined. The calorific value and yield of the product gas, cold gas efficiency, and carbon conversion increase with increasing fluidization gas velocity and reaction temperature. With increasing air/coal ratio, carbon conversion, cold gas efficiency and yield of the product gas increase, but the calorific value of the product gas decreases. When steam/coal ratio is increased, cold gas efficiency, yield and calorific value of the product gas increase, but carbon conversion is little changed. Unburned carbon fraction of cyclone fine decreases with increasing fluidization gas velocity, reaction temperature and air/coal ratio, but is nearly constant with increasing steam/coal ratio. Overall carbon conversion decreases with increasing fluidization velocity and air/ coal ratio, but increases with increasing reaction temperature. The particle entrainment rate increases with increasing fluidization velocity, but decreases with increasing reaction temperature. This paper is dedicated to Professor Dong Sup Doh on the occasion of his retirement from Korea University.