Seashell waste-derived materials for secondary catalytic tar reduction in municipal solid waste gasification

Abstract

Catalytic tar removal from producer gas is critical for the economic feasibility of Municipal Solid Waste (MSW) gasification in the waste-to-energy(WtE) approach. Nickel-and noble-metal catalysts have the highest tar cracking activities, but they increase costs, use scarce materials, and generate dangerous byproducts. To overcome these drawbacks, naturally occurring materials should be used for tar cracking. In this paper, two nanomaterials, synthesized from oyster and mussel waste shells respectively, are used to clean syngas from MSW in a secondary tar cracking unit. We observed that they reform class 1 tar (heavy tars that condense at high temperatures at very low concentrations) into class 3 tar (light hydrocarbons that are not important in condensation) and benzene. Although both catalysts' composition and textural properties were identical, crystallite size and especially specific surface area variation was enough to generate a change in product selectivity.A larger crystallite size and SSA shows a soot yield reduction of 95% with respect to the non-catalytic case, simultaneously increasing the H 2 /CO at 1000 • C.

Review on Catalytic Biomass Gasification for Hydrogen Production as a Sustainable Energy Form and Social, Technological, Economic, Environmental, and Political Analysis of Catalysts

“…Oyster and mussel waste shells have been employed to synthesize nanomaterials to produce clean syngas from MSW. 237 Both catalysts similarly increased gas yields at 800 °C. The oyster-derived catalysts exhibited a higher tar removal at higher temperature (1000 °C) because of their effect on syngas yield, and they decreased the soot yield by improving the quality of syngas.…”

“… 236 On the contrary, Ni, Pt, Pd, Rh, and Ru possess the highest catalytic activity, long-duration stability, and low carbon deposition through tar cracking, but they are rare in nature and not economically sustainable. 237 …”

“…Although this kind of waste material suffers from properties like impurities, lower surface area, etc., it is a good option for minimizing waste and reducing environmental impacts . On the contrary, Ni, Pt, Pd, Rh, and Ru possess the highest catalytic activity, long-duration stability, and low carbon deposition through tar cracking, but they are rare in nature and not economically sustainable …”

“…Oyster and mussel waste shells are calcium-rich materials that can be used for tar removal instead of calcined dolomite and olivine, as they do not need to be mined and have less adverse effects on the environment. Oyster and mussel waste shells have been employed to synthesize nanomaterials to produce clean syngas from MSW . Both catalysts similarly increased gas yields at 800 °C.…”

The EU Training Network for Resource Recovery through Enhanced Landfill Mining—A Review

“…This study was cited with respect to tar generation and conversion kinetics [96], regarding the required high temperatures of 1100 • C which represent a disadvantage compared to catalytic reforming [97], and as an example for thermal tar cracking [98]. Finally, two CaO-rich catalysts doped with Sr were synthesized from mussel shells and successfully tested for tar cracking in the syngas [99].…”