Catalytic and Noncatalytic Gasiﬁcation of Wood– Coconut Shell Blend Under Different Operating Conditions M. Inayat, a S. A. Sulaiman, a J. C. Kurnia, a and M. Y. Naz b a Department of Mechanical Engineering, Universiti Teknologi PETRONAS, 32610 Bandar Seri Iskandar, Perak Darul Ridzuan, Malaysia; muddasser_engr@yahoo.com (M. Inayat for correspondence) b Department of Physics, University of Agriculture, 38040 Faisalabad, Pakistan; Department of Physics, University of Agriculture, 38040 Faisalabad, Pakistan Published online 5 October 2018 in Wiley Online Library (wileyonlinelibrary.com). DOI 10.1002/ep.13003 The formation of tar during biomass gasiﬁcation is a main barrier to establishing reliable gasiﬁcation technologies. Differ- ent catalysts are being used for tar abatement from the bio- mass gasiﬁcation. In this study, catalytic and noncatalytic cogasiﬁcation of wood-coconut shell blends was carried out in a downdraft gasiﬁer. The effect of the operating parameters on syngas quality, performance of cogasiﬁcation, and tar reduc- tion was investigated. The biomass blending ratio (BR) was varied as W20:CS80, W50:CS50, and W80:CS20, equivalence ratio (ER) was varied from 0.19 to 0.35, gasiﬁcation tempera- ture from 700 to 900  C and catalyst loading (CL) from 5 to 30%. Dolomite, limestone, and Portland cement were used as a catalyst. The results revealed that under noncatalytic condi- tions, the blend with higher proportion of coconut shells pro- duces better syngas composition with higher HHV and lower tar content. The high ER reduced H 2 , tar formation, cold gas efﬁciency and gas yield. It also improved the carbonaceous gas species and carbon conversion efﬁciency. Increasing gasi- ﬁcation temperature signiﬁcantly improved the syngas quality, cogasiﬁcation performance and reduced the tar content. The 30% CL signiﬁcantly improved the gas composition content, gas yield, cold gas efﬁciency and reduced the tar content up to 52%. Better syngas quality and cogasiﬁcation performance was possible with calcined cement catalyst whereas a reduc- tion in tar content was observed in the presence of limestone. © 2018 American Institute of Chemical Engineers Environ Prog, 38: 688–698, 2019 Keywords: catalytic co-gasiﬁcation, blending ratio, cement, dolomite, syngas INTRODUCTION Gasiﬁcation is a thermochemical conversion technique that converts carbonaceous solid fuel like biomass into useful com- bustible gaseous fuel (syngas). In this process, partial oxidiza- tion of the solid fuel at a temperature range of 700–1000  C takes paces followed by series of complexed reactions, as summarized in Table 1 [1]. Syngas is a fuel gas that can be used in an I.C engine or in a gas turbine for power generation. It can also be utilized as a feedstock for the Fischer-Tropsch process to convert gaseous fuels into high-grade liquid fuels based on H 2 /CO ratio [4]. Typically, syngas consists of H 2 , CO, CH 4 , CO 2 , C 2 H 4 and unwanted complex hydrocarbon is known as tar. Tar is the most troublesome contaminant of syngas, [5] and one of the most technically challenging component in estab- lishing a reliable commercial biomass gasiﬁcation technology for power generation [6]. High tar concentration in the syngas may reduce the performance of I.C engines and gas turbines and increase the maintenance cost [7]. Therefore, tar removal from the syngas is essentially required for its sophisticated utili- zation. In general, tar removal methods can be categorized into primary and secondary methods. The primary method corresponds to the tar removal inside the gasiﬁer by varying the operating parameters or using additive materials (catalyst). In secondary method, the tar removal is carried out outside the gasiﬁer by using mechanical ﬁlters, cyclones, and scrub- bers [8]. The mechanical methods or secondary method merely removes the tar from the gas phase to condensable phase while primary catalyst application or thermal degradation of tar is very attractive as tar components can be fully devastated and converted into useful products [9]. The thermal degradation follows a series of tar decomposi- tion mechanizes like thermal cracking, steam reforming, dry reforming, carbon formation and partial oxidation as presented in Table 2 [10,11]. In these reactions, C n H x and C m H y repre- sented tar and hydrocarbon, respectively. C n H x is the combina- tion of various organic compounds whereas C m H y is a lower carbon number as compared to C n H x . The tar generation in the gasiﬁcation process is a result of series of complex reactions occurring simultaneously. The tar formation tremendously relies on the reaction conditions [10], such as temperature [5], equivalence ratio (φ), feedstock type, feedstock composition, blending ratio [12], and catalyst appli- cation, etc. The temperature and equivalence ratio (ratio of actual air supplied to stoichiometric air for complete combus- tion) are key operating parameters for the gasiﬁcation process, which simultaneously affect the reaction mechanisms, tar for- mation, and its composition. Typically, the temperature has inﬂuenced at all stages of the thermochemical process includ- ing; fuel devolatilization, solid to gas conversion, and char gas- iﬁcation reactions [5]. Similarly, blending ratio can inﬂuence the gasiﬁcation outcomes by governing the H/C ratio of raw © 2018 American Institute of Chemical Engineers 688 March/April 2019 Environmental Progress & Sustainable Energy (Vol.38, No.2) DOI 10.1002/ep