The effects of cornstalk addition on the product distribution and yields and reaction kinetics of lignite liquefaction Fan Zhang a,b , Deping Xu a , Yonggang Wang a , Xiangkun Guo c , Long Xu b,d , Maohong Fan b,e,⇑ a School of Chemical and Environmental Engineering, China University of Mining and Technology, Beijing 100083, PR China b Department of Chemical and Petroleum Engineering, University of Wyoming, Laramie, WY 82071, USA c School of Materials Science and Engineering, Henan Polytechnic University, Jiaozuo 454003, PR China d School of Chemical and Engineering, Northwest University of China, Xi’an 710069, PR China e School of Energy Resources, University of Wyoming, Laramie, WY 82071, USA highlights  The product distribution and yields during the cornstalk-assisted direct coal liquefaction were studied.  The reaction from preasphaltene to asphaltene was the rate-limiting step at 360 °C.  The reaction from asphaltene to oil was the rate-limiting step at 420 °C.  A kinetic model of the cornstalk-assisted direct coal liquefaction was proposed. article info Article history: Received 3 February 2014 Received in revised form 27 April 2014 Accepted 16 May 2014 Available online 4 June 2014 Keywords: Cornstalk Lignite Co-liquefaction Product distribution Kinetics abstract The cornstalk-assisted direct lignite liquefaction was conducted by using a resonance agitation micro-autoclave heated by a salt bath. The effects of reaction temperature (360 °C, 390 °C, and 420 °C) and time (5 min, 15 min, 30 min, and 60 min) on the distribution and yields of liquefaction products (asphaltene, preasphaltene, oil, and gas) were investigated. The results show that the reaction tempera- ture has significant effect on the distribution and yields of products in the cornstalk-assisted direct coal liquefaction. At 360 °C, the reaction from preasphaltene to asphaltene is the rate-limiting step of the overall co-liquefaction process, while at 420 °C the reaction from asphaltene to oil becomes the rate- limiting step. A kinetic model is proposed and the kinetics analysis shows that the activation energy for the reaction from raw material to preasphaltene and asphaltene is 41.9 kJ/mol, while that for the reaction from preasphaltene and asphaltene to oil and gas is 61.4 kJ/mol. The addition of cornstalk can considerably improve the reaction kinetics of the co-liquefaction of Shengli coal and cornstalk. Published by Elsevier Ltd. 1. Introduction As one of the most important fossil fuels, coal and its utilization technologies have attracted increasing attention from energy and chemical researchers. Since the CO 2 emissions resulting from coal combustion have become problematic [1–5] and are limiting the development of the coal industry, many researchers are increas- ingly interested in advanced coal utilization technologies such as coal gasification [6–9] and liquefaction. These new technologies are characterized by higher energy utilization efficiency and lower CO 2 emissions. It is well known that coal is readily available in China while petroleum is scarce. Since the 1990s, oil consumption in China has grown quickly and continuously. In 2012, crude oil imports accounted for 58.7% of the total oil consumption in China, which indicates that China will face a large energy security challenge. Part of the solution to this challenge is to produce fuels from coal through direct coal liquefaction (DCL). However, DCL requires operating conditions of high temperature and pressure and an oil quality improvement process [10]. Until these issues are resolved, DCL technologies cannot be widely commercialized. Biomass resources are not only readily available, but also renew- able, thus their utilization for energy production is promising [11]. Compared to coal, biomass has a higher mole ratio of hydrogen/ carbon and is more easily liquefied. Scholars have studied co-lique- faction of coal and biomass since the 1990s. Akash et al. [12] studied http://dx.doi.org/10.1016/j.apenergy.2014.05.033 0306-2619/Published by Elsevier Ltd. ⇑ Corresponding author at: Department of Chemical and Petroleum Engineer- ing, University of Wyoming, Laramie, WY 82071, USA. Tel.: +1 307 766 5633; fax: +1 307 766 6777. E-mail address: mfan@uwyo.edu (M. Fan). Applied Energy 130 (2014) 1–6 Contents lists available at ScienceDirect Applied Energy journal homepage: www.elsevier.com/locate/apenergy