Catalytic and Noncatalytic Mechanisms in Steam Gasification of Char from the Pyrolysis of Biomass^†

Abstract

Steam gasification of chars from the pyrolysis of a Japanese bamboo and cedar was studied using a reactor that enabled experimental definition of the gas composition in the vicinity of gasifying char particles. Intraparticle diffusion of neither steam nor the product gases influenced the kinetics of gasification. The chars underwent noncatalytic and catalytic gasification in parallel. The noncatalytic gasification, in which kinetic parameters were successfully defined by those for the gasification of the acid-washed char, was first-order with respect to the amount of residual carbon over the entire range of char conversion. In consequence of this, contribution of the catalytic gasification was quantified as a function of the char conversion. Among the inherent alkali and alkaline earth metallic species, potassium (K) played the major catalytic role and its overall activity changed via a maximum in the course of gasification, suggesting the presence of optimum sizes of clusters or particles of K catalyst. The noncatalytic and catalytic reactions obeyed respective Langmuir−Hinshelwood mechanisms that involved inhibition by H2.

Production of ketones from pyroligneous acid of woody biomass pyrolysis over an iron-oxide catalyst

“…The chips have an average size of 10  10  2 mm, 50.9 wt.% carbon and 3 -3-wt.% moisture content. The pyrolysis was carried out with a feeding rate, an average residence time, a heating rate, a peak temperature, and a gas pressure inside the reactor of 270 g h −1 , 47 s, 5.0-5.5 C s −1 , 500 C, and 1.0 atm, respectively [2]. The slow pyrolysis produces char, heavy tar, light tar which consist of two separate phases: organic liquid (water-insoluble fraction) and pyroligneous acid (water-soluble fraction), and gaseous products.…”

“…Sustainability in energy recovery from biomass such as steam gasification of char is becoming attractive because biomass to energy conversion adds no additional greenhouse gases to the atmosphere [1,2]. The char as highquality solid fuel is produced from pyrolysis and its higher yield can be recovered by slow pyrolysis than fast or flash ones [3,4].…”

Steam Gasification of Sawdust Biochar Influenced by Chemical Speciation of Alkali and Alkaline Earth Metallic Species

“…In the current investigation, many researchers [13][14][15][16][17][18] found that alkali and alkaline earth metallic species (AAEMs) dispersed in biomass and/or biochar as different chemical speciations, play significant catalytic roles in biochar gasification reactivity, and that AAEMs volatilized as a gaseous phase would also take part in homogeneous reforming reactions [19]. The concentration and dispersion of AAEMs, according to the results obtained by Wu et al [20], is a significant factor affecting the catalytic activity of AAEMs during biomass gasification, which varies constantly due to the carbon consumption and the release/migration of AAEMs [21,22].…”

Recovery of Resources from End-of-life Industrial Products by Using Liquefaction or Gasification

“…Moreover, toxic organic halogen compounds are converted to stable and safe inorganic salts by carbonates, so the gaseous products generated should be halogen-free and can be used as fuel. Gasification in the presence of carbonates had been proposed for coal 17) and other heavy hydrocarbons 18) . The catalytic effect of potassium in coal gasification has also been reported in many previous studies 19) .…”