Research Article Simulation Analysis of a Gas-to-Liquid Process Using Aspen Plus Gas-to-liquid (GTL) processes are becoming attractive due to the increasing price of crude oil. Process simulation analysis on the integrated GTL process is essential as part of an extended process integration analysis of the research subjects. The two sub-process models for the GTL process, i.e., the syngas generation process and the Fischer Tropsch synthesis (FTS) process, are analyzed in detail with AS- PEN Plus. The autothermal reforming process (ATR) is analyzed using Aspen Plus based on the Gibbs reactor model, while FTS is simulated with ASPEN Plus based on detailed kinetic models for industrial iron and cobalt catalysts. Inte- grated GTL processes with iron and cobalt-based catalysts were simulated using ASPEN Plus. The optimal flowsheet structures were selected for each catalyst based on the overall performance in terms of thermal and carbon efficiency and product distributions. For the cobalt-based catalyst, the full conversion concept without CO 2 removal from the FT tail gas is optimal. On the other hand, the once-through concept with two series reactors and CO 2 removal from raw syngas is considered optimal for the iron-based catalyst. The thermal efficiency to crude products is likely to be ca. 60 % for the cobalt-based catalyst, whereas it is in the range of 49–55 % for the iron-based catalyst. The carbon efficiency using the water-gas shift reaction is lower using the iron-based catalyst (61–68 %) than the cobalt-based catalyst (73–75 %). As expected, the cobalt-based catalyst is more active and selective, which offers better selectivity towards C 5 + (75–79 %). The selectivity towards C 5 + for the iron-based catalyst lies in the range 63–75 %. Keywords: Gas-to-Liquid process, Simulation, Syngas Received: September 18, 2007; revised: October 31, 2007; accepted: November 06, 2007 DOI: 10.1002/ceat.200700336 1 Introduction The interest in FT synthesis (FTS) has grown as a consequence of stringent environmental regulations, technological develop- ments and changes in fossil energy reserves. One attractive op- tion is to use syngas derived from natural gas to produce ultra- clean fuel through the Fischer-Tropsch process (GTL). It can be matched directly with conventional fuel markets without any specific modification to the existing distribution infra- structure. In 1993, Shell started up the first commercial plant for conversion of natural gas to liquid fuels in Bintulu, Malay- sia [1]. China with the world’s biggest population is well-known for its large coal reserve. It also has large proven natural gas re- sources of 1.95 trillion cubic meters, mainly in the remote de- serts of the western region and offshore. Since crude oil supply is insufficient for its domestic oil demand, FT-diesel produced either from coal or natural gas should become a replacement for oil-based products. A pilot-plant scale of the CTL process has already been running since 2002 at the Institute of Coal Chemistry, Chinese Academy of Sciences and a commercial scale CTL plant will be realized in the near future. The development of the GTL process in China is still in its infancy. Supported cobalt-based catalysts have been developed for many years by Synfuels China, the State Key Laboratory of Coal Conversion – Institute of Coal Chemistry (ICC). Due to the availability of natural gas and recent technological develop- ments, the GTL process may now have attractive economical and environmental aspects for China’s fuel market. In general, the main objective of this study is to construct and investigate the optimal flowsheet structure for the inte- grated GTL process using two developed FT catalysts, i.e., iron and cobalt-based catalysts. This can be obtained by using a process simulation analysis with ASPEN Plus. It is also impor- tant to investigate the feasibility of the introduction of the © 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim http://www.cet-journal.com Xu Hao 1,2 Martina Elissa Djatmiko 3 Yuanyuan Xu 1 Yining Wang 1 Jie Chang 1 Yongwang Li 1 1 State Key Laboratory of Coal Chemistry, Chinese Academy of Sciences, Taiyuan, P. R. China. 2 Graduate School of Chinese Academy of Sciences, Beijing, P. R. China. 3 Delft University of Technology, Delft, The Netherlands. – Correspondence: Y. W. Li (ywl@sxicc.ac.cn) and X. Hao (haoxu@sxicc.- ac.cn), State Key Laboratory of Coal Chemistry, Institute of Coal Chemistry, Chinese Academy of Sciences, Taiyuan 030001, P. R. China. 188 Chem. Eng. Technol. 2008, 31, No. 2, 188–196