Compositional Features of the Light Fraction from One/Two-Step Effective Cascade Catalytic Hydroconversion of the Extraction Residue from Naomaohu Lignite

摘要

Naomaohu lignite(NL)was extracted with isometric acetone/carbon disulfide mixed solvent under ultrasonic irradiation.The extraction residue(ER)was subjected to non-catalytic hydroconversion(_(NCHC))and one/two-step cascade catalytic hydroconversion(CHC)in n-hexane at 300℃ under 4 MPa of H2 over magnetic solid superacid(MSSA)and superbase(MSSB).The _(NCHC)-soluble portion from the _(NCHC)(SP_(NCHC))and CHC-soluble portion from the one/two-step cascade CHC(SPA,SPB,SP_(A-B),and SP_(B-A))were analyzed with a gas chromatograph/mass spectrometer(GC/MS).The results show that the yields of SPA and SPB are 18.65% and 16.31%,respectively,which are much higher than that of SP_(NCHC)(1.26 %).According to the analysis with GC/MS,SPA and SPB are rich in phenol,dimethylnaphthalene,cresol,trimethylphenols,and xylenols,while alkanes are the predominant group component in the SP_(NCHC),indicating that MSSA selectively catalyzed the cleavage of C_(ar)-C_(alk)and C_(alk)-O bridged bonds,whereas MSSB tended to cleave C_(ar)-O and C_(alk)-O bridged bonds connecting some aromatic rings in the ER.The yield of SP_(B-A)was as high as 11.07% and SP_(A-B)was only 0.59 %.The results showed that more soluble species in the ER could be further released through the cascade CHC procedures.Benzyloxybenzene was used as a coal-related model compound to probe the possible mechanisms of one/two-step cascade CHC of the ER.