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• PET steam gasification in a bubbling fluidized bed was studied. • Steam was the main source of H 2 , while CO 2 was the main gaseous product. • The product distribution was more sensitive to temperature than other variables. • More than half of C converted to tars, while biphenyl doubled from 750 to 800 °C. • The results provide references for mixed fuel gasification when PET is involved. Polyethylene terephthalate (PET) is widely used in textile fiber, film, and bottles. Although PET bottle recycling has made great progress, other PET waste is still not recycled. Gasification could be an option for recycling or recovering energy and chemicals from PET waste. However, single stream PET steam gasification in fluidized bed is seldom investigated. In this paper, individual PET gasification experiments were then conducted in a lab-scale bubbling fluidized bed to investigate how gasifying agents, temperature, residence time and steam/fuel ratio affect the product composition. The results showed that, in steam gasification, steam was the main source of H 2 , but increasing the steam to fuel ratio cannot increase the H 2 yield remarkably. Temperature was an essential parameter. Increasing temperature from 750 to 800 °C improved the yields of H 2 (+87.7%), the dominant gas product CO 2 (+40.3%), and biphenyl (+123%) notably. In contrast to other common thermoplastics, high concentrations of CO 2 and biphenyl are the prominent characteristics of PET steam gasification. In addition, plastic steam gasification optimizations for syngas applications were discussed. [ABSTRACT FROM AUTHOR]

• In-bed catalysis during steam cracking of linear hydrocarbons was studied. • Ash activated olivine shows clear changes on the product gas composition. • Higher yields of permanent gases were obtained at expenses of aromatic compounds. • Higher hydrocarbons follow steam reforming routes instead of aromatization paths. • Activated olivine is able to decompose aromatic precursors towards permanent gases. In this work, the effect of ash activated olivine on olefinic products cracking and aromatization was assessed. The experiments were carried out in the Chalmers 2–4 MW th dual fluidized bed gasifier, where the feedstock was cracked using steam as fluidization agent, at a reaction temperature of ca. 780–790 °C. Three activation states of the olivine, representing three consecutive days of the campaign, were evaluated. The changes of the permanent gas composition along with the reduction in aromatic species with the time of exposure to biomass ash demonstrate a clear effect of the ash activated olivine on the conversion of olefinic cracking products. The ash activation of the olivine clearly promoted the reactions involving steam. As a consequence, higher yields of permanent gases, mainly H 2 , CO and CO 2 , were produced at expenses of the yields of the total aromatic compounds and C 4 hydrocarbons and larger. It is concluded that the biomass ash activated olivine promotes the steam reforming path of the C 4 and larger hydrocarbon fragments, while avoiding the alternative aromatization route. The results presented here provide useful insights on the opportunities and limitations of ash activated materials in DFB systems when steam cracking linear hydrocarbon feedstocks, e.g., polyolefin-based materials. [ABSTRACT FROM AUTHOR]