1 Yuan, X.Q., Liu, J.Q., Guo, C.T.. Coal Chem. Eng., 46(1), 48(1989). 2 Gu, Z.H., Li, Y.C., Chemical Engineer, 53(2):21(1996). 3 Jens, W., Manfred, S., Stefan, E., J. Chem. Soc. Chem. Comm., 56(10), 1133(1991). 4 Jens, W., Manfred, S., Stefan, E., German patent 3940428, June 13, 1991. 5 Tan, X.Y., Wang, X.Sh., J Dalian Univ. Tech., 37(3), 351(1997). |