ZEOLITE 4A FOR CLEANSING OF LANDFILL GAS

The anaerobic decomposition in landfills produces a gas mixture known as landfill biogas. This biogas consists mainly of CH4 and CO2. The CO2 removal can be carried out by means of adsorption. In order to promote CO2 removal, zeolite type 4A was used as solid adsorbent. The synthesized zeolite was characterized by scanning electron microscopy and X-ray diffraction. CH4/CO2 mixture isotherms were obtained in a magnetic suspension balance equipped with a gas dosing unit and Extended Langmuir and Extended Sips models were used to predict mixture isotherms from monocomponent data. Three biogas emissions drains in a sanitary landfill in Caucaia (Ceará State, Brazil) - ASMOC - were chosen to test the performance of zeolite as CO2 adsorbent under real conditions. Zeolite 4A has proven to be very selective for CO2 even in the presence of H2S.

垃圾填埋场中的厌氧分解会产生一种被称为填埋场生物气的混合气体。该生物气主要由甲烷（CH4）与二氧化碳（CO2）组成。脱除二氧化碳可采用吸附法。为强化二氧化碳脱除效果，本研究选用4A型沸石（zeolite type 4A）作为固体吸附剂。所合成的沸石通过扫描电子显微镜（scanning electron microscopy）与X射线衍射（X-ray diffraction）完成了表征。本研究借助配备气体定量进样单元的磁悬浮天平，测得甲烷/二氧化碳混合气体吸附等温线，并采用扩展朗缪尔（Extended Langmuir）模型与扩展希普斯（Extended Sips）模型，基于单组分吸附数据预测混合气体吸附等温线。研究选取巴西塞阿拉州考卡亚市一座卫生填埋场内的三处生物气排放口（ASMOC），用于测试4A型沸石作为二氧化碳吸附剂在实际工况下的吸附性能。实验证实，即便在硫化氢（H2S）共存的条件下，4A型沸石仍对二氧化碳表现出优异的选择性。