PREPARATION OF BIOCHARS FOR CO-GASIFICATION FROM SWEET SORGHUM BAGASSE

摘要

Biochar is a solid product obtained through torrefaction, liquefaction or pyrolysis of organic material.rnIt can be used for soil amendment, activated carbon for sequestration, or as bio-coal for gasification or cogasification.rnA recent patent on GreenCoal showed the potential of biochar to lower sulphur emissions and increaserncoal reactivity during co-gasification with low grade discard coal. Co-gasification of biochar and coal with increasedrnreactivity, translated to increased syngas production using existing synthetic fuel plants without the need forrnmodifications to accommodate biomass in the feed. In this study biochar for co-gasification purposes was producedrnfrom sweet sorghum bagasse using hydrothermal liquefaction at low heating rates (2.5 K.min~(-1)) in large (1 L)rnreactors. The effect of reaction temperature and biomass loading on biochar yield and characteristics wererninvestigated with and without the addition of a calcite (CaCO_3) catalyst. Prepared biochars were characterised usingrnSEM, ultimate analysis, proximate analysis, BET, XRD/XRF and FTIR. High biochar yields (558.7 g.kg~(-1) bagasse)rnwere obtained with very little oil and gas products forming. Biochar yields decreased with an increase in temperaturernand increased with an increase in biomass loading. Elemental analysis showed an increased higher heating valuern(HHV) for all the prepared chars compared to the original bagasse. Characterisation of the chars showed that thernadditional of a calcite catalyst increased the biochar yields and significantly changed the structure of the chars. Thernstudy showed that lignocellulose materials such as sweet sorghum bagasse can be used to prepare biochars withrncharacteristics similar to young lignite coal, without the minerals and sulphur present it coal.