C02 ADSORPTION ISOTHERM OF LAKAT COAL RELATED TO THEIR CHEMICAL AND ORGANIC COMPOSITION Muh. Rizki Ramdhani (a,b), Yan Rizal (a), Sigit Arso Wibisono (b), Muh. Arief Pinandita (b), Rizki Satria Rachman (b)
(a) Geological Engineering Department, Faculty of Earth Science and Technology, Institut Teknologi Bandung
(b) Center for Mineral, Coal, and Geothermal Resources, Geological Agency, Ministry of Energy and Mineral Resources
Abstract
Deep seated coal seams are one of the attractive options for geological CO2 sequestration. These seams are particularly interesting due to their ability in adsorb gas especially CO2. Indonesia has great potential in deep seated coal as in Lakat Formation which located in Central Sumatera Basin. The objective of this study is to determine the CO2 adsorption capacity in Lakat Coal related to their chemical and organic composition. In this context, several analyses were conducted in three Lakat coal samples such as proximate, ultimate, petrography, and adsorption isotherm analyses. Moisture and Ash content are varied from 13,48% to 19,66% and 5,27% to 25,74% in as received basis respectively. Calorific value of these samples ranging from 5.246 to 6.885 cal/gr. Vitrinite reflectance vary from 0,54 to 0,57. The maceral composition is dominated by vitrinite (76,8% to 86,2%). The inertinite and liptinite content is 5,6 to 6,2% and 1,6 to 11,4% respectively. According to the ASTM, the rank of these coals is classified from Subbituminous A to High Volatile C Bituminous. The adsorption isotherm analyses were performed at 33 degrees celcius and absolute pressure from 0,24 MPa to 6,78 MPa. The CO2 sorption capacity vary from 2,1 to 25,98 cc/gr in as received basis and 3,16 to 31,56 cc/gr in dry ash free basis. The CO2 sorption capacity in this study is affected by moisture content, ash content, and maceral composition. Ash and inertinite content show negative relationship with CO2 sorption capacity, while fixed carbon and vitrinite content present positive relationship. Moisture content exhibit weak positive relationship with CO2 sorption capacity. These analyses will support CCS/CCUS study in deep seated coal seams by providing the information of CO2 maximum holding capacity in Lakat coal and their relationship to its chemical and organic composition.
Keywords: CO2 adsorption capacity, Lakat Coal, Organic Composition, Chemical Composition
