CO₂ Gasification of Sugar Cane Bagasse: Quantitative Understanding of Kinetics and Catalytic Roles of Inherent Metallic Species

Abstract

A total of 18 chars from the pyrolysis of six trios of sugar cane bagasses (SCBs; original, water-washed, and acid-washed) were gasified with CO2 at 900 °C, aiming at a quantitative description of the rate of gasification catalyzed by inherent metallic species and a correlation of the catalytic activity and its change during the gasification with the metallic species composition. The measured kinetics was described quantitatively over a range of char conversion, 0–0.999, by a model that assumed progress in parallel of the catalytic gasification and non-catalytic gasification, together with the presence of a catalytic precursor and three to four types of catalysts having different activities and deactivation characteristics. A series of regression analyses was scrutinized and reached expression of initial catalytic activity as a linear function of Na, K, Ca, Fe, and Si concentrations in the char with a correlation factor (r 2) of >0.98. The catalyst precursor contributed fully by water-soluble Na, K, and Ca. Si was responsible for the catalyst deactivation during the pyrolysis but not during the gasification. The chars produced from original SCBs followed a linear relationship between the initial catalytic deactivation rate and initial activity (r 2 > 0.99), while such a linear relationship was not valid for those formed from the water-washed SCBs. This was explained mainly by more rapid deactivation of the Fe catalyst in the chars from water-washed SCBs than that in the chars formed from the original SCBs. Na and K in char from the original SCBs, originating from the water-soluble SCBs, chemically interacted with the Fe catalyst, slowing its deactivation.

Re-examination of Thermogravimetric Kinetic Analysis of Lignite Char Gasification

“…Note that not only AAEM but also Fe species are inherent in the LY char . Its catalytic effect was, however, very limited as a result of the lower activity than AAEM species as well as rapid deactivation. ,,− …”

“…] , vary along with the gasification, influencing the kinetics. Recent studies on CO 2 gasification of chars from lignites and biomass reported that the rate of gasification was described well by the following equation: − where X , k 1 , and k 2 are the char conversion and rate constants for non-catalytic gasification and catalytic gasification, respectively. It assumes the non-catalytic and catalytic reactions in parallel.…”

“…It assumes the non-catalytic and catalytic reactions in parallel. According to the reports, − the non-catalytic gasification obeyed first-order kinetics with respect to the unconverted fraction of char, although this kinetics has not necessarily been fully proven . It is also believed that k 2 varies as a function of X as a result of the change in the overall catalytic activity …”

“…13 It is also believed that k 2 varies as a function of X as a result of the change in the overall catalytic activity. 12 The present authors have been investigating both the noncatalytic and catalytic gasification by measuring and analyzing the kinetics via thermogravimetric analysis (TGA). On the way to conclude the above-described kinetics, difficulty arose in determining the rate of gasification free from the mass transfer effect.…”

6th Sino-Australian Symposium on Advanced Coal and Biomass Utilisation Technologies

“…Zahara et al ( 10.1021/acs. energyfuels.7b03147) 23 from the combustion of a single coal char particle under oxyfuel conditions. Li et al (10.1021/acs.energyfuels.7b03105) 31 report the effect of acidic gases (NO x and SO 2 ) on the removal of Hg 0 in an oxy-fuel CO 2 compression process.…”