Hydrogen production by catalytic gasification of coal in supercritical water with alkaline catalysts.pdf

i n t e r n a t i o n a l j o u r n a l o f h y d r o g e n en e r g y 3 9 ( 2 0 1 4 ) 1 9 5 8 3e1 9 5 9 2Available online at wScienceDirect journal homepage: www.elsevier .com/locate/heHydrogen production by catalytic gasification of coal in supercritical water with alkaline catalysts: Explore the way to complete gasification of coalZhiwei Ge, Hui Jin, Liejin Guo* State Key Laboratory of Multiphase Flow in Power Engineering, Xian Jiaotong University, Xian 710049, Chinaa r t i c l e i n f o Article history: Received 17 April 2014 Received in revised form 17 September 2014 Accepted 22 September 2014 Available online 12 October 2014 Keywords: Supercritical water Coal Gasification Hydrogen Catalyst* Corresponding author. Tel.: t86 29 8266 38 E-mail address: lj-guo@ ( /10.1016/j.ijhydene.2014.09.1 0360-3199/Copyright ? 2014, Hydrogen Enera b s t r a c t Supercritical water gasification (SCWG) of coal is a promising technology for clean coal utilization. In this paper, hydrogen production by catalytic gasification of coal in super- critical water (SCW) was carried out in a micro batch reactor with various alkaline cata- lysts: Na2CO3, K2CO3, Ca(OH)2, NaOH and KOH. H2 yield in relation to the alkaline catalyst was in the following order: K2CO3 z KOH z NaOH Na2CO3 Ca(OH)2. Then, hydrogen production by catalytic gasification of coal with K2CO3 was systematically investigated in supercritical water. The influences of the main operating parameters including feed con- centration, catalyst loading and reaction temperature on the gasification characteristics of coal were investigated. The experimental results showed that carbon gasification efficiency (CE, mass of carbon in gaseous product/mass of carbon in coal
100%) and H2 yield increased with increasing catalyst loading, increasing temperature, and decreasing coal concentration. In particular, coal was completely gasified at 700 C when the weight ratio of K2CO3 to coal was 1, and it was encouraging that raw coal was con