Journal of Natural Gas Chemistry 21(2012)7–10 Removal of high concentration CO 2 from natural gas at elevated pressure via absorption process in packed column L. S. Tan, K. K. Lau, M. A. Bustam, A. M. Shariff ∗ CO 2 Management MOR, Universiti Teknologi PETRONAS, 31750 Tronoh, Perak, Malaysia [ Manuscript received June 30, 2011; revised August 9, 2011 ] Abstract Carbon dioxide (CO 2 ) removal is an essential step in natural gas (NG) processing to provide high quality gas stream products and minimize operational difficulties. This preliminary study aims to investigate the removal of CO 2 at high concentration level from the mixture of CO 2 -NG gas stream at elevated pressure via absorption process. This is to explore the possibility of exploring high CO 2 content natural gas reserves by treatment at offshore platform. A mixed amine solvent, Stonvent-II, was used for the absorption of approximately 75 vol% CO 2 in CO 2 -NG stream at a pressure of 10 barg. The initial solvent temperature was varied in order to study the impact of initial temperature on the absorption performance. Preliminary study at temperatures of 35 ◦ C and 45 ◦ C indicates that Stonvent-II was able to perform almost 100% removal of CO 2 under both conditions. However, the CO 2 absorption effect took place faster when the initial liquid temperature was lower. This is because when the initial liquid temperature is high, the temperature increase in the packing bed caused by the reaction heat is high which impacts the efficiency of absorption negatively. Key words CO 2 capture; absorption; packed column; amine; mild pressures 1. Introduction CO 2 removal is an essential process in the sweetening of natural gas from underground reservoir. Natural gas gener- ally contains a large quantity of methane along with heavier hydrocarbons such as ethane, propone, isobutene, normal bu- tane and considerable amount of CO 2 . CO 2 must be removed from natural gas, because CO 2 is highly corrosive in the pres- ence of moisture (water) which rapidly destroys pipelines and equipment. It also reduces the heating value of a natural gas stream and wastes pipeline capacity [1]. In steam reforming of natural gas, it is also important to separate CO 2 from H 2 in the precombustion capture process before H 2 could be fed into combustion turbine [2]. Natural gas in commercial operations includes variable amounts of CO 2 ranging from CO 2 -free natural gas in Siberia to as high as 90% CO 2 content in the Platong and Erawan fields in Thailand. The Natuna field in the Greater Sarawak Basin in Indonesia is the largest gas field in south Asia, with estimated 46 trillion cubic feet recoverable reserves. Unfortu- nately, it remains unexplored due to high CO 2 content of 71% [3]. In Malaysia, CO 2 content in natural gas fields varies from 28%-87%. Over 13 trillions cubic feet natural gas reserves are undeveloped due to high CO 2 content [4]. High CO 2 gas fields in Malaysia represent an excellent opportunity for sig- nificant CO 2 capture and storage (CCS). Many researches are conducted on the removal of CO 2 from natural gas [5-8], and absorption processes with chem- ical solvents are currently the most used technology for CO 2 separation from natural gas and post-combustion CO 2 capture commercially, because they are much more efficient and cost effective compared with other processes thus far [9]. In re- cent years, various experimental works are carried out to fur- ther investigate the efficiency of packed column in CO 2 re- moval [8,10-15]. Packed column are commonly used as a means of promoting efficient contact between gases and liq- uids. It could offer high mass transfer efficiency with low pressure drop [16]. Nevertheless, the level of CO 2 concentra- tion in initial gas stream investigated by other researchers is only between 10% to 20% so far and most of the researches are conducted under atmospheric pressure condition [7,8,11, 14,17-20]. The motivation of those researches is mainly to reduce or control CO 2 concentration in the atmosphere by re- moving CO 2 from flue gas. However, in our study, the main motivation is to open up the possibility of exploring high CO 2 content natural gas ∗ Corresponding author. Tel: +60-605-3687570; Fax: +60-605-3656176; E-mail: azmish@petronas.com.my Copyright©2012, Dalian Institute of Chemical Physics, Chinese Academy of Sciences. All rights reserved. doi:10.1016/S1003-9953(11)60325-3