小型高温高压反应器及加压炭催化ch4co2重整研究
太原理工大学 硕士学位论文 小型高温高压反应器及加压炭催化CH/CO重整研究 姓名:张丙模 申请学位级别:硕士 专业:化学工艺 指导教师:张永发 20100501 太原理工大学硕士研究生学位论文 II 小型高温高压反应器及加压炭催化 CH4/CO2重整研究 摘 要摘 要 CH4-CO2重整技术有效地将甲烷利用和二氧化碳转化结合在一起,获 得适合费托、甲醇和羰基合成的原料气,近年来,相关研究受到广泛关注。 尤其是笔者所在课题组开展的焦炉煤气中 CH4和气化煤气中 CO2重整制合 成气技术,该技术作为“双气头”多联产系统的关键技术之一,2005 年获得 了国家重大基础研究发展计划(973 计划)的支持。技术经济分析表明,如 果甲烷二氧化碳重整反应能在加压(24MPa)下进行,可以降低过程的能 耗。尽管增加压力不利于体积增大的 CH4-CO2重整反应,但是在课题组承 担的“973” 项目炭催化 CH4-CO2重整研究中期评估会上,评估专家经 过认真、深入的讨论,提出“增加开展加压炭催化 CH4-CO2重整研究”的要 求。本文根据专家要求开展了常压和加压炭催化 CH4-CO2重整实验研究。 首先研究开发了小型高温高压反应器,以该小型反应器为核心搭建了一套 高温高压反应系统,然后在小型高温高压反应装置上系统地研究了反应压 力、反应温度、原料气配比、停留时间等因素对炭催化 CH4-CO2重整反应 的影响。采用 BET、红外光谱和 SEM 等现代仪器分析手段对炭催化剂进行 积碳、比表面积、孔径、吸附量、含氧官能团等分析,探讨了炭催化剂结 构和催化特性。获得的主要结果和研究结论如下: 1. 采用高温区平衡压力,高压区降低温度的原理,研究开发出一种内 加热式小型高温 (1200) 高压 (12MPa) 反应器, 其加热段长度为 400mm; 太原理工大学硕士研究生学位论文 III 石英反应管的内径为 30mm;反应器不同位置留有四个测温孔。 2. 建 立 了 小 型 反 应 器 基 本 传 热 方 程 , 反 应 器 温 度 分 布 模 型 714ln1300TR=,用传热方程确定了保温材料厚度 120mm;确定了反 应器主体圆筒、封头和小法兰厚度分别为 40mm、23.2mm 和 75mm;反应 器轴向温度呈梯型分布,加热段存在长度为 25cm 的恒温区;在给定反应压 力的条件下,反应器外表面的温度基本不变;小型反应器完全符合设计和 实验要求。 3. 炭催化剂对 CH4裂解和 CH4-CO2重整反应都具有明显的催化作用。 在 950, 停留时间 6s 条件下, 非催化 CH4裂解中甲烷的转化率小于 5.0%, 炭催化 CH4裂解中甲烷转化率达到 20.6%; 非催化 CH4-CO2重整反应中 CH4 和 CO2转化率都小于 5.0%,炭催化条件下 CH4和 CO2转化率分别为 50.0% 和 72.3%,充分证明了炭催化剂在甲烷裂解和 CH4-CO2重整反应中的催化 作用。 4. 炭催化 CH4-CO2重整反应中, 随着温度的提高 CH4和 CO2的转化率 迅速增大;升高反应压力,CH4和 CO2的转化率降低;停留时间的延长, 有利于甲烷和二氧化碳重整反应的进行,提高甲烷二氧化碳转化率。 5. 炭催化条件下 CH4和 CO2的转化率开始较高,一段时间后逐渐降低 并趋于稳定,这主要是由炭催化剂中活性物质逐渐被消耗或者活性中心被 积炭覆盖而导致的催化剂活性降低所引起的。 6. 采用 SEM、BET 和 FITR 等分析手段对炭催化剂进行了表征。分析 表明,原样炭催化剂中的炭可分为边沿炭和本体炭两类。边沿炭有较高的 催化活性和气化反应性,但很快被消耗;本体炭的催化活性和气化反应性 太原理工大学硕士研究生学位论文 IV 都较低,但可保持较长时间的催化活性;反应前后炭催化剂的比表面积和 孔容发生较大变化,表明其比表面和孔容是影响催化剂活性的重要影响因 素;反应前后的 FITR 表明含氧官能团是炭催化剂活性物质之一,并且参与 了重整反应。 7. 在 750800温度范围内计算了甲烷二氧化碳重整反应的平衡常 数,根据实验平衡常数回归的范特霍夫方程为:24116.7/26.958lnKT= +, 实验平衡常数与理论值基本一致。 关键词:炭催化,甲烷二氧化碳重整,高温高压,小型反应器 太原理工大学硕士研究生学位论文 VII HIGH TEMPERATURE -PRESSURE REACTOR AND DRY REFORMING METHANE OVER CARBON CATALYST UNDER PRESSURE ABSTRACT CH4-CO2 reforming technology effectively combines CH4 utilization with CO2 transforming and gets raw gases for Fischer-Tropsch, methanol and carbonyl synthesis. In recent years, this study field becoming active, particularly, our group developed a technology of reforming CH4 in coke oven gas with CO2 in gasification gas to make syngas, which was one of the key technologies about "dual-gas resources polygeneration system" and won the support of the National Key Basic Research Development Plan (973 plan) in 2005. Technical and economic analysis shows that process energy consumption would be reduced if the reforming reaction was in the pressure of 24Mpa. Although increasing pressure is a disadvantageous to the CH4-CO2 reforming with increased volume, the experts in the mid-term assessment of "973" projectCarbon catalytic reforming study of CH4-CO2expressed requirements of increasing the pressure in carbon catalytic reforming reaction of CH4-CO2 after careful in-depth discussion. On the basis of the requirement, this study carried out with C-catalyzed CH4-CO2 reforming with normal pressure and high pressure. First of all, a small high temperature-pressure reactor was developed and a high temperature- pressure reactor system was built in the core of the small reactor. 太原理工大学硕士研究生学位论文 VIII Then the influence factors of reaction pressure, reaction temperature, raw gas ratio and residence time to carbon catalytic reforming reaction of CH4-CO2 were studied in the high temperature-pressure reactor. TG, N2 absorption, infrared spectroscopy, SEM and other means of modern instruments were employed to study the characteristic of C-catalyst, such as coke deposition, specific surface area, pore size, absorption, the oxygen functional groups, also the structure and catalytic characteristic of carbon catalyst were discussed. The main results of research and conclusions are as follows. 1. Based on the principle of “pressure balance in high temperature zone and lower temperature reactor which sustains pressure”, a small reactor working at high-temperature and high-pressure (1200, 12Mpa) has been developed. Heating section length of reactor is 400mm. Diameter of quartz was 30mm. Four holes were left on reactor for detecting temperature. 2. The basic heat transfer equation of reactor was established, which is a better response of temperature distribution in a small reactor. The thickness of insulation material is 120mm. Temperature distribution of reactor is 714ln1300TR=. The thickness of reactor main body is 40mm. The thickness of head is 23.2mm. The thickness of flange is 75mm. Axial temperature of reactor within 25cm was basically consistent. The temperature range between 25cm can be regarded as constant temperature zone; With increasing of reaction pressure the surface temperature of the reactor is basically constant. Small reactor comply requirements of design and experiment. 太原理工大学硕士研究生学位论文 IX 3.Carbon catalyst has