• Energy Research
• 2021-2025close
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Abstract A requirement for the development of a viable biomass conversion technology for clean energy production is the efficient cleaning of the gas fraction. The aim of this work was to use fly ash (AF) to develop cheap and efficient catalysts in removing tar. FA was separated in two fraction, oxide fly ash (OFA) and unburned carbon (UCFA) and both were used for catalysts preparing. The toluene was used as a tar model and a fixed-bed reactor for testing. The calcined oxide fly ash (COFA) showed a steady decrease in catalytic activity, the removal efficiency was reduced by 13.52% after 3 h. Reduced catalyst (RCOFA) and activated and reduced catalyst (AROFA) showed a higher activity than COFA catalyst and were able to maintain their performance. The RCOFA catalytic activity decreased suddenly when the steam was present, and tar removal efficiency descended to 57.32% after only 3 h and to 49.03% after 5hrs, respectively. Results showed that the catalysts obtaining by mixing RCOFA/AROFA with UCFA led to high effective toluene conversion in a reforming environment, over 90% and their catalytic activity remained constant after 12 h, because the unburned carbon presence kept the iron in its reduced form, much more catalytically active.

Abstract Sunlight Concentrated and transmission for daylighting via optical fibers is a booming technology of direct utilization of solar energy. It uses optical fibers to introduce sunlight deep into building interior. In this work, a sunlight concentrating and transmitting system via plastic optical fibers was developed and tested. This study addressed the cooling problem of the plastic optical fibers under highly irradiation. Polymethylmethacrylate (PMMA) plastic fibers have a strong absorption effect on infrared light, which means that plastic fibers heat up so much when they transmit focused sunlight that they burn. In this study, a comprehensive cooling approach was developed to solve the overheating problem of plastic optical fibers, which consists of an infrared filter, cooling water and a homogenizer. The transmission efficiency of the system was measured to be about 15%. Experiments show that the comprehensive cooling measures developed can ensure that PMMA plastic optical fibers are in a safe temperature range. This shows that it is feasible to use low-cost plastic optical fibers instead of expensive silica fiber to transmit high flux for daylighting.

Abstract In the present study, Ru modified hierarchical zeolites xRu-MZSM were developed for cellulose fast pyrolysis. Comprehensive catalyst characterizations including XRD, XPS, N2 adsorption-desorption, Py-IR and so on, were performed to unveil the essential structural properties. The chemical modification and Ru decoration remarkably regulated the distribution of Bronsted/Lewis acid sites. The presence of RuOx species would supply abundant strong Lewis acid sites for participating catalytic cracking, dehydration, decarbonylation, decarboxylation, cyclization, aromatization, etc., in cooperation with Bronsted acid sites. In-situ generated active Ru0 centers during cellulose pyrolysis might facilitate the proceeding of deoxygenation, hydride transfer, and dehydrogenation. Among the as-prepared catalysts screened, 2Ru-MZSM was much more efficient in aromatics production from cellulose fast pyrolysis compared to parent ZSM, wherein the total aromatics yield achieved 16.8% at temperature of 650 °C and heating rate of 10 °C/ms with corresponding E value as low as 23.40 kJ/mol. Also, plausible reaction mechanism for xRu-MZSM involved cellulose fast pyrolysis was proposed in detail.