Methanation System for Upgrading Landfill Gas into Pipeline Quality Renewable Natural Gas by Thermocatalytic Conversion of CO2

可再生天然气（RNG）可以从垃圾填埋气（LFG）中生产，LFG是有机材料分解的产物。由于LFG含有大量的CO2（高达55体积%），因此必须在使用前进行处理，这通常通过使用变压吸附或膜分离进行分离。然而，这种方法与高资本投资和操作成本相关，并且用于利用分离的CO2的市场有限。另一种方法是通过热催化甲烷化反应将LFG中所含的CO2转化为CH4，该反应是通过使CO2与氢气（H2）在催化床上反应。氢可以通过使用无碳排放的可再生能源（风能，太阳能，水力）或低成本剩余电力电解水来产生。将LFG升级为RNG，其与管道质量天然气完全互换，是LFG燃烧的有益替代方案。使用清洁能源将垃圾填埋气升级为可再生天然气，以替代化石天然气，减少发电及住宅供暖所产生的整体碳排放。RNG的使用可以支持现有的天然气供应系统，同时消耗富含温室气体的捕获原料，并且可以用作电力到天然气基础设施的一部分，用于剩余能量存储和再分配。

Renewable natural gas (RNG) can be produced from landfill gas (LFG), a product of the decomposition of an organic material. Since LFG contains large amounts of CO2 (up to 55 vol%), it must be processed prior to use, which is conventionally done by separation using pressure swing adsorption or membrane separation. However, this approach is associated with high capital investment and operating costs and markets for utilization of separated CO2 are limited. An alternative approach is to convert the CO2 contained in LFG into CH4 via the thermocatalytic methanation reaction, by reacting CO2 with hydrogen (H2) over a catalytic bed. Hydrogen can be generated by water electrolysis using carbon emission-free renewable energy sources (wind, solar, hydro) or low-cost surplus electricity. Upgrading LFG to RNG, which is fully interchangeable with the pipeline quality natural gas, is a beneficial alternative to the LFG flaring. The use of clean energy sources for LFG upgrading to RNG as a substitute to fossil natural gas reduces the overall carbon emission resulted from power generation and residential heating. The use of RNG can bolster the existing natural gas supply system, while consuming captured feedstocks rich in greenhouse gases, and can be utilized as part of a power-to-gas infrastructure for surplus energy storage and redistribution.