Granular activated carbons from palm nut shells for gold di-cyanide adsorption

Granular activated carbons were produced from palm nut shells by physical activation with steam. The proximate analysis of palm nut shells was investigated by thermogravimetric analysis, and the adsorption capacity of the activated carbons, produced as a result of shell pyrolysis at 600℃ followed by steam activation at 900℃ in varying activation times, was evaluated using nitrogen adsorption at 77 K. Applicability of the activated carbons for gold dicyanide adsorption was also investigated. Increasing the activation hold time with the attendant increase in the degree of carbon burn-off results in a progressive increase in the surface area of the activated carbons, reaching a value of 903.1 m2/g after activation for 6 h. The volumes of total pores, mieropores, and mesopores in the activated carbons also increase progressively with the increasing degree of carbon burn-off, resulting from increasing the activation hold time. The gold di-cyanide adsorption of the activated carbons increases with the rise of pore volume of the activated carbons. The gold di-cyanide adsorption of palm nut shell activated carbon obtained after 6-h activation at 900℃ is superior to that of a commercial activated carbon used for gold di-cyanide adsorption.

Three-stage pyrolysis–steam reforming–water gas shift processing of household,commercial and industrial waste plastics for hydrogen production

Five common single plastics and nine different household,commercial and industrial waste plastics were processed using a three-stage(i)pyrolysis,(ii)catalytic steam reforming and(iii)water gas shift reaction system to produce hydrogen.Pyrolysis of plastics produces a range of different hydrocarbon species which are subsequently catalytically steam reformed to produce H_(2)and CO and then undergo water gas shift reaction to produce further H_(2).The process mimics the commercial process for hydrogen production from natural gas.Processing of the single polyalkene plastics(high-density polyethylene(HDPE),low-density polyethylene(LDPE),and polypropylene(PP))produced similar H_(2)yields between 115 mmol and 120 mmol per gram plastic.Even though PS produced an aromatic product slate from the pyrolysis stage,further stages of reforming and water gas shift reaction produced a gas yield and composition similar to that of the polyalkene plastics(115 mmol H_(2)per gram plastic).PET gave significantly lower H_(2)yield(41 mmol per gram plastic)due to the formation of mainly CO,CO_(2)and organic acids from the pyrolysis stage which were not conducive to further reforming and water gas shift reaction.A mixture of the single plastics typical of that found in municipal solid waste produced a H_(2)yield of 102 mmol per gram plastic.Knowing the gas yields and composition from the single plastics enabled an estimation of the yields from a simulated waste plastic mixture and a‘real-world’waste plastic mixture to be determined.The different household,commercial and industrial waste plastic mixtures produced H_(2)yields between 70 mmol and 107 mmol per gram plastic.The H_(2)yield and gas composition from the single waste plastics gave an indication of the type of plastics in the mixed waste plastic samples.

Correction to:Decomposition of biomass gasification tar model compounds over waste tire pyrolysis char

Correction to:Waste Disposal&Sustainable Energy(2022)4:75-89 https:/doi.0rg/10.1007/s42768-022-00103-5 The section'Conflict of Interest'has been amended;'Paul T.Williams is the Editorial Board member of Waste Disposal&Sustainable Energy.'The revised'Conflict of Interest'is as follows:Paul T.Williams is the Editorial Board member of Waste Disposal&Sustainable Energy.On behalf of all authors,the corresponding author states that there is no conflictof interest.

Decomposition of biomass gasification tar model compounds over waste tire pyrolysis char

Gasification of biomass produces a syngas containing trace amounts of viscous hydrocarbon tar,which causes serious problems in downstream pipelines,valves and processing equipment.This study focuses on the use of tire-derived pyrolysis char for tar conversion using biomass tar model compounds representative of tar.The catalytic decomposition of tar model compounds,including methylnaphthalene,furfural,phenol,and toluene,over tire char was investigated using a fixed bed reactor at a bed temperature of 700℃and 60 min time on stream.The influence of temperature,reaction time,porous texture,and acidity of the tire char was investigated with the use of methylnaphthalene as the tar model compound.Oxygenated tar model compounds were found to have higher conversion than those containing a single or multi-aromatic ring.The reactivity of tar compounds followed the order of furfural>phenol>toluene>methylnaphthalene.The conversion of the model compounds in the presence of the tire char was much higher than tar thermal cracking.Gas production increased dramatically with the introduction of tire char.The H_(2)potential for the studied tar model compounds was found to be in the range of 40%–50%.The activity of tire char for naphthalene removal was compared with two commercial activated carbons possessing a very well-developed porous texture.The results suggest that the influence of Brunauer-Emmett-Teller surface area of the carbon on tar cracking is negligible compared with the mineral content in the carbon samples.

Co-pyrolysis-catalytic steam reforming of cellulose/lignin with polyethylene/polystyrene for the production of hydrogen

Co-pyrolysis of biomass biopolymers(lignin and cellulose)with plastic wastes(polyethylene and polystyrene)coupled with downstream catalytic steam reforming of the pyrolysis gases for the production of a hydrogen-rich syngas is reported.The catalyst used was 10 wt.%nickel supported on MCM-41.The influence of the process parameters of temperature and the steam flow rate was examined to optimize hydrogen and syngas production.The cellulose/plastic mixtures produced higher hydrogen yields compared with the lignin/plastic mixtures.However,the impact of raising the catalytic steam reform-ing temperature from 750 to 850 ℃was more marked for lignin addition.For example,the hydrogen yield for cellulose/polyethylene at a catalyst temperature of 750 ℃was 50.3 mmol g^(−1) and increased to 60.0 mmol g^(−1) at a catalyst temperature of 850°C.However,for the lignin/polyethylene mixture,the hydrogen yield increased from 25.0 to 50.0 mmol g^(−1) repre-senting a twofold increase in hydrogen yield.The greater influence on hydrogen and yield for the lignin/plastic mixtures compared to the cellulose/plastic mixtures is suggested to be due to the overlapping thermal degradation profiles of lignin and the polyethylene and polystyrene.The input of steam to the catalyst reactor produced catalytic steam reforming conditions and a marked increase in hydrogen yield.The influence of increased steam input to the process was greater for the lignin/plastic mixtures compared to the cellulose/plastic mixtures,again linked to the overlapping thermal degradation profiles of the lignin and the plastics.A comparison of the Ni/MCM-41 catalyst with Ni/Al_(2)O_(3) and Ni/Y-zeolite-supported catalysts showed that the Ni/Al_(2)O_(3) catalyst gave higher yields of hydrogen and syngas.