甲醇水蒸气重整制氢固定床反应器的数学模拟

建立二维拟均相固定床反应器数学模型用于描述Cu₅₀Zn₃₀Ce₁₀Al₁₀催化剂颗粒的甲醇水蒸气重整制氢反应过程,该模型由流体相的质量、热量和动量传递方程组成,耦合催化剂颗粒内部的扩散-反应模型。通过将模型预测值与实验数据进行比较,验证反应器数学模型的准确性。在此基础上,分析关键组分CO₂和CO的效率因子随床层轴向的变化规律以及催化剂床层的轴径向温度分布。结果表明：催化剂床层的轴径向温差较大,导致CO₂效率因子变化较大,而CO由于浓度低,反应速率慢,其效率因子变化不明显。     

甲烷部分氧化及重整反应多相催化剂的研究进展

介绍国内外甲烷制合成气技术中多相催化剂的研究进展,包括催化剂在水蒸气重整、甲烷部分氧化和二氧化碳重整制合成气技术中的研究情况,重点评述了催化剂的活性组分、助剂和载体方面的研究进展及存在的问题。     

不同结构微反应器下甲烷水蒸气重整制氢性能对比

微通道反应器是便携式制氢领域目前最有发展前景的技术之一。为了提高甲烷水蒸气重整在微反应器内制氢的效果,设计了三种不同结构的微反应器几何模型,分别为直管(Pipe)模型、平板圆弧弯道(FCC)模型和三纹内螺旋枪管(Tri-g ISB)模型,利用Ansys Fluent流体仿真软件结合甲烷水蒸气重整制氢的CHEMKIN反应机理文件对三种不同结构的微反应器进行了数值模拟分析。通过研究不同条件下微反应器出口气体组分变化可知,入口速度越小,CH₄转化率和H₂体积分数越高;S/C>3时,CH₄转化率增大至80%以上、H₂含量增加至73vol%以上;壁面温度越大,CH₄转化率可稳定在99.9%,几乎完全转化,H₂含量增大到77vol%以上,但温度过高会降低H₂产量,增加CO含量。通过计算不同条件下微反应器达到稳定所需时间可知,随入口速度和S/C增加稳定时间均逐渐减小并趋于稳定,随壁面温度增加,稳定时间先减小后增加。通过对比三种微反应器可知,复...     

Ni/γ-Al_2O_3催化剂上甲烷水蒸气重整制合成气

采用固定床装置,考察了负载型Ni系列催化剂及反应条件对Ni/γ-Al2O3催化剂的甲烷水蒸气重整反应的影响,并利用XRD和TPR技术对催化剂样品进行表征。结果表明,在空速1 800 h-1,n(H2O)∶n(CH4)∶n(N2)=2.86∶1∶3.28,反应温度700℃的条件下,催化剂Ni含量在9%时反应性能最佳,可得到94.3%的CH4转化率和64.9%的CO选择性。     

一种吸附增强甲烷水蒸气重整制氢反应装置及方法

本发明公开了属于石油化工技术领域的一种吸附增强甲烷水蒸气重整制氢反应装置及方法。该装置包括混合器、格栅式流化床反应器、旋风分离器、再生反应器、第一料封、第二料封。该方法主要包括格栅式流化床反应器吸附增强甲烷水蒸气重整和吸附剂煅烧再生两个主要步     

板翅式反应器中甲醇水蒸气重整制氢

研制了一种高效板翅式反应器,其特点是体积相对较小,便于放置,便于扩大规模;集预热、气化、重整、催化燃烧于一体;板翅式反应器内部热量利用合理,放热反应与吸热反应、气化与冷却之间实现了较好的热量耦合;可实现完全自供热.在反应器中进行了一系列甲醇水蒸气重整的实验,考察了不同条件对甲醇重整制氢过程的影响、对反应器床层温度分布的影响,及反应器的稳定性.另外,由于板翅式结构的良好传热性,甲醇水蒸气重整在获得较高转化率的同时重整气中CO浓度较低,且反应器的稳定性良好.     

甲醇水蒸气重整制氢催化剂性能的研究

研究共沉淀法制备Cu/Al2O3甲醇水蒸气重整制氢催化剂，考察催化剂组成和焙烧温度对催化剂性能的影响。结果表明当Cu质量分数为30．9％，焙烧温度为500℃时，催化剂性能最佳。并采用X射线衍射（XRD），程序升温还原（TPR）和热重分析等方法对催化剂表面性质进行探讨。     

用于甲烷二氧化碳重整反应的Ni基催化剂的研究进展

对用于甲烷二氧化碳重整反应的Ni基催化剂的研究进展进行了概述,详细分析了Ni金属结构形态、载体、助剂及制备方法等方面对Ni基催化剂活性、稳定性及抗积碳性能的影响。     

低温高活性甲醇水蒸气重整制氢催化剂的研究

氢气具有无污染,易转化成热能、电能和机械能等特点,所以有人预计,在下一世纪,氢能将取代大部分矿物燃料,在汽车、飞机、火电站、工业炉及家庭中广泛使用,最今后的主要二次能源之一。     

介微孔分子筛催化剂在甲烷重整反应中的研究进展

针对甲烷重整制氢技术,重点论述了ZSM-5、SBA-15和MCM-41分子筛催化剂不同的制备方法和采用金属粒子对催化剂进行修饰等手段对各种甲烷重整制氢反应的作用规律;在改进分子筛结构方面,尤其是针对甲烷水蒸汽反应的难点提出了相应建议。     

Computational study of staged membrane reactor configurations for methane steam reforming. II. Effect of number of stages and catalyst amount

The present work complements part I of this article and completes a computational analysis of the performances of staged membrane reactors for methane steam reforming. The influence of the number of stages and catalyst amount is investigated by comparing the methane conversion and hydrogen recovery yield achieved by an equisized‐staged reactor to those of an equivalent conventional membrane reactor for different furnace temperatures and flow configurations (co‐ and counter‐current). The most relevant result is that the proposed configuration with a sufficiently high number of stages and a significantly smaller catalyst amount (up to 70% lower) can achieve performances very close to the ones of the conventional unit in all the operating conditions considered. This is equivalent to say that the staged configuration can compensate and in fact substitute a significant part of the catalyst mass of a conventional membrane reactor. To help the interpretation of these results, stage‐by‐stage temperature and flux profiles are examined in detail. Then, the quantification of the performance losses with respect to the conventional reactor is carried out by evaluating the catalyst amount possibly saved and furnace temperature reduction. © 2009 American Institute of Chemical Engineers AIChE J, 2010     

用于分布式制氢的甲烷蒸汽重整膜反应器的数值模拟

采用反应-分离集成的膜反应器进行分布式制氢,对简化工艺、降低能耗、提升技术经济性至关重要。本文采用数学模型对甲烷蒸汽重整制氢过程膜反应器进行模拟,系统分析了渗透侧操作策略、反应压力、反应温度、钯基膜性能、催化剂性能对反应器行为的影响;并以1m³/h甲烷最大程度转化为目标进行分布式制氢案例分析,详细比较膜反应器技术与“常规反应器+膜分离”工艺技术。结果表明,膜反应器在反应压力30atm（1atm=101325Pa）、反应温度500℃下操作可实现紧凑设计,比“常规反应器+膜分离”工艺技术具有明显优势,但是亟需研发更佳活性（10倍）的钯基膜和催化剂以实现显著的过程强化。模拟结果可为不同规模分布式制氢膜反应器的操作与设计及进一步的性能强化提供指导。     

Intrinsic kinetics of nickel/calcium aluminate catalyst for methane steam reforming

A new catalyst for steam reforming of methane based on nickel/calcium aluminate is prepared. The new catalyst has shown stability and high activity at low steam to methane ratios. In this paper the intrinsic rate equations are derived and parameters estimation made. The rate equations show non-monotonic dependence on steam partial pressure. The rate equations also show that the primary product is CO₂ while CO is formed via the reverse water-gas shift reaction. The mechanism proposed and the rate equations obtained indicate that it may be essential to propose specific rate models for any given catalyst rather than generalized mechanism and rate models.     

Theoretical and experimental analysis of methane steam reforming in a membrane reactor

Thermal effects on methane steam reforming process were analyzed, in a Pd-Ag (23wt%) membrane reactor as a function of several parameters, such as temperature, reactant and sweep-gas flow rate, and reactant molar ratio. Heat transfer from the oven was very important for the outlet methane conversion, which also depends on the temperature profile along the reactor. In particular, when the reactant flow rate was high the conversion degree decreased because the energy supplied was not sufficient to maintain the temperature in the reactor. A non-isothermal mathematical model was presented which reproduced the experimental data.     

Pure hydrogen production by methane steam reforming with hydrogen-permeable membrane reactor

Low temperature steam reforming of methane mainly to hydrogen and carbon dioxide (CH₄ + 2H₂O → 4H₂ + CO₂) has been performed at 773 and 823 K over a commercial nickel catalyst in an equilibrium-shift reactor with an 11-μm thick palladium membrane (Mem-L) on a stainless steel porous metal filter. The methane conversion with the reactor is significantly higher than its equilibrium value without membrane due to the equilibrium-shift combined with separation of pure hydrogen through the membrane. The methane conversion in a reactor with an 8-μm membrane (Mem-H) is similar to that with Mem-L, although the hydrogen permeance through Mem-H is almost double of that through Mem-L. The amount of hydrogen separated in the reaction with Mem-H is significantly large, showing that the hydrogen separation overwhelms the hydrogen production because of the insufficient catalytic activity.     

Particle‐resolved simulations of methane steam reforming in multilayered packed beds

Particle‐resolved CFD simulations of multilayered packed beds containing 30 particles of different particle shapes (trilobe, daisy, hollow cylinder, cylcut, and 7‐hole cylinder) with a tube to particle diameter ratio of 5, were performed to understand the effect of particle shape on pressure drop (ΔP), dispersion, CH₄ conversion and effectiveness factors for methane steam reforming reactions. The effect of different boundary conditions and particle modeling approaches were analyzed in detail. The empirical correlations (Ergun and Zhavoronkov et al.) over‐predicted the ΔP and a modified correlation was developed to predict ΔP for the particles with different shapes. Overall, the externally shaped particles (trilobe and daisy) offered lower ΔP and higher dispersion because of the lower surface area and higher back flow regions, whereas the internally shaped particles (cylcut, hollow, and 7‐hole cylinder) offered higher CH₄ conversion and effectiveness factors because of the better access for the reactants. The cylcut‐shape offered the highest CH₄ conversion/ΔP. © 2018 American Institute of Chemical Engineers AIChE J, 64: 4162–4176, 2018     

Process intensification aspects for steam methane reforming: An overview

Steam methane reforming (SMR) is the most widely used process in industry for the production of hydrogen, which is considered as the future generation energy carrier. Having been perceived as an important source of H₂, there are abundant incentives for design and development of SMR processes mainly through the consideration of process intensification and multiscale modeling; two areas which are considered as the main focus of the future generation chemical engineering to meet the global energy challenges. This article presents a comprehensive overview of the process integration aspects for SMR, especially the potential for multiscale modeling in this area. The intensification for SMR is achieved by coupling with adsorption and membrane separation technologies, etc., and using the concept of multifunctional reactors and catalysts to overcome the mass transfer, heat transfer, and thermodynamic limitations. In this article, the focus of existing and future research on these emerging areas has been drawn. © 2009 American Institute of Chemical Engineers AIChE J, 2009     

On the reported attempts to radically improve the performance of the steam methane reforming reactor

Steam reforming of light hydrocarbons is a key step for producing hydrogen and syngas for important processes in the petroleum and petrochemical industries. Since the establishment of the SMR process in 1930, research and development have led to improved catalyst performance and improved reactor tube materials. Since about 1970, new reactor configurations have been considered. The authors critically review recent attempts to radically improve the SMR reactor performance, analyze the areas of improvement and the suitability of proposed configurations for different reforming applications.     

Innovative steam methane reforming for coproducing CO-free hydrogen and syngas in proton conducting membrane reactor

Steam methane reforming (SMR) is a commercial process to produce syngas. Normally, the as-produced syngas is characterized by a H₂/CO ratio of 3. However, such H₂/CO ratio is unsuitable for Fischer–Tropsch synthesis. The hydrogen obtained by subsequent upgrading of syngas usually contains residual CO, which readily deactivates Pt electrocatalysts in fuel cells. Here we report an innovative route by coupling SMR with H₂ removal in a proton conducting membrane reactor to coproduce syngas with a preferable H₂/CO ratio of 2 and CO-free H₂ on opposite sides of the membrane, which can be directly used for Fischer–Tropsch synthesis and fuel cells, respectively. Notably, H₂ is in-situ extracted by the membrane that only allows the permeation of H₂ as protons through the oxide lattice with infinite selectivity, and thus the obtained H₂ is CO-free. This work could provide an alternative option in one-step conversion of methane into two inherently separated valuable chemicals.