| 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 2~4Mpa. Although increasing pressure is a disadvantageous to the CH4-CO2 reforming with increased volume, the experts in the mid-term assessment of "973" project《Carbon catalytic reforming study of CH4-CO2》expressed 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. 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 T =? 714ln R? 1300. 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. 3.Carbon catalyst has obvious catalytic effect on CH4 decomposition and CH4-CO2 reforming. At 950℃, conversion rate of CH4 in decomposition of methane was less than 5.0% under non-catalytic, while it reach 20.6% under carbon catalytic. The uncatalyzed CH4 and CO2 conversion are lower than 5%, while catalyzed CH4 and CO2 conversion reach 50.0% and 72.3% respectively in the CH4-CO2 reforming reaction. The facts indicate that CH4 decomposition and CH4-CO2 reforming reaction catalyzed by C-catalyst.4. With temperature increasing, the conversion rate of CH4 and CO2 rapidly increase . With the reaction pressure increasing , the conversion rate of CH4 and CO2 decrease . Prolonging residence time is in favor of CH4-CO2 reforming reaction, which promotes the conversion of CH4 and CO2.5.The conversion of CH4 and CO2 is high during initial of stage of the reaction, and then decays to a relatively fixed value after a period of time. The main reason is that the consumption of active component of carbon catalyst and the coke cover of active sites.6.The products were characterized and analyzed through SEM, BET and FITR. The carbon micro clusters in carbon catalyst could be divided into two types: edge carbon micro clusters and bulk carbon micro clusters. The edge carbon micro clusters have high catalytic activity and gasification reactivity, The catalytic activity and gasification reactivity of bulk carbon micro clusters are low relatively, but it can maintain certain catalytic activity for longer time. The BET results show that, compared with original carbon catalyst, the surface area and pore volume of carbon catalyst has been greatly changed after reaction, indicating that the surface area and pore volume carbon catalyst are confirmed to be one important factor affecting the catalytic activity. The oxygen functional groups such as C-O, C=O and O=C-O were found on the surface by FTIR, the results show the C-O was decreased.7. The equilibrium constant of CH4-CO2 reforming was calculated at 750～800℃. The Van't Hoff equation LnK=–24116.7/T+26.985 was obtained by equilibrium constant regression.The result indicated that the experimental equilibrium constant is consistent with the theoretical result.
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