Henrik Romar

Characterisation and Catalytic Fischer–Tropsch Activity of Co–Ru and Co–Re Catalysts Supported on γ-Al2O3, TiO2 and SiC

A number of supported cobalt catalysts for Fischer–Tropsch synthesis were considered. Catalysts were prepared by impregnation of the supports with a cobalt precursor resulting in cobalt concentrations of 15 or 20 wt%. The active metal was supported onto aluminum oxide, titanium dioxide and silicon carbide supports while rhenium or ruthenium metals were used as promoters, whose concentrations were 0, 0.2 or 1.0 wt%. The catalysts were characterized by a number of methods including BET, chemisorption, and XRD. Some of the catalysts were tested for catalytic activity and selectivity in the Fischer–Tropsch reaction using a fixed bed reactor. Based on the results, the addition of promoter metals increases the dispersion of the active metal cobalt and correspondingly a decrease in the cobalt metal particles, this effect was most evident for the alumina supported catalysts. Further, increased concentrations of the ruthenium promoter (1.0 wt%) slightly increased the selectivity to CH4 and decreased selectivity to C5+.

Characterization of Cobalt Catalysts on Biomass-Derived Carbon Supports

Cobalt catalysts are known to have a high activity and selectivity in the Fischer–Tropsch reaction converting synthesis gas to higher hydrocarbons (C5+). These catalysts have been supported by different porous materials. Porous carbon materials like activated carbon (AC) have physical and chemical surface properties that affect the preparation of supported metal catalysts and can easily be tailored. In this study, AC was produced by carbonization and steam activation of lignin, a waste fraction from the Kraft pulping process. A series of Co/AC-catalysts was produced and characterized by several techniques. According to the results, tailored properties (high surface area, mesoporosity) were obtained for carbon supports. Further, ash content could be reduced by acid treatment. Co/AC-catalysts prepared by ultrasonic assisted impregnation have high metal dispersion (10.1%). It was also observed that small metal particles were difficult to reduce, but acid (HNO3) treatment has a positive effect on reduction temperatures.

Activated Carbon from Renewable Sources: Thermochemical Conversion and Activation of Biomass and Carbon Residues from Biomass Gasification

Activated carbon is one of the most widely applied adsorbent. As a porous carbon, it is used for the purification of both gaseous and liquid emissions. Activated carbon is prepared from fossil resources, such as coal, or from biomass through (hydro)thermal processing followed by chemical and/or physical activation. Further, some biomass thermal treatment processes, such as biomass gasification, produce carbon residues that can be modified to activated carbon with physical or chemical activation methods. The desired properties of activated carbon, i.e. high specific surface area and porosity, high carbon content and excellent sorption capacity, can be modified and optimized during thermochemical treatment and activation. Those properties, which are shortly considered, are important in different applications for activated carbon.

Physico-Chemical Properties and Use of Waste Biomass-Derived Activated Carbons

Physico-Chemical Properties and Use of Waste BiomassDerived Activated Carbons Riikka Lahti*, Davide Bergna, Henrik Romar, Tero Tuuttila, Tao Hu, Ulla Lassi University of Oulu, Research Unit of Sustainable Chemistry, P.O.Box 3000, FI-90014 University of Oulu, Finland University of Jyvaskyla, Kokkola University Consortium Chydenius, Applied Chemistry, P.O.Box 567, FI-67101 Kokkola, Finland riikka.lahti@chydenius.fi

Bisphenol A removal from water by biomass-based carbon: isotherms, kinetics and thermodynamics studies

ABSTRACT Biomass-based carbon was modified and used as an efficient bisphenol A (BPA) sorbent. The simple and environmentally friendly modification method produced sorbent with a capacity of 41.5 mg/g. The raw material was modified with FeCl3 (Fe-CR), treated with hydrochloric acid (H-CR) or modified with CaCl2 (Ca-CR). Batch sorption experiments were performed to evaluate the effects of the initial pH, sorbent dosage, temperature, and contact time on BPA removal. BPA removal with modified carbons was notably higher than that with unmodified carbon. All sorbent materials exhibited very high sorption capacities and compared favourably to materials reported in the literature. Several isotherms were applied to describe the experimental results of Fe-CR, H-CR, and Ca-CR modified carbon residues and the Sips model showed the best fit for all sorbents. Kinetic studies for the best sorbent material (Fe-CR) showed that the sorption process follows Elovich kinetics. Desorption cycles were implemented, and sorption capacity remained with three cycles. GRAPHICAL ABSTRACT

Study of Ni, Pt, and Ru Catalysts on Wood-based Activated Carbon Supports and their Activity in Furfural Conversion to 2-Methylfuran

Bio‐based chemicals can be produced from furfural through hydrotreatment. In this study, 2‐methylfuran (MF), a potential biofuel component, was produced with Pt, Ru, and Ni catalysts supported on wood‐based activated carbons. The catalytic hydrotreatment experiments were conducted in a batch reactor at 210–240 °C with 2‐propanol as solvent and 40 bar H2 pressure. Two types of activated carbon supports were prepared by carbonization and activation of lignocellulosic biomass (forest‐residue‐based birch and spruce from Finland). Both types of activated carbons were suitable as catalyst supports, giving up to 100 % furfural conversions. The most important factors affecting the MF yield were the metal dispersion and particle size as well as reaction temperature. The highest observed MF yields were achieved with the noble metal catalysts with the highest dispersions at 240 °C after 120 min reaction time: 3 wt % Pt on spruce (MF yield of 50 %) and 3 wt % Ru on birch (MF yield of 49 %). Nickel catalysts were less active most likely owing to lower dispersions and incomplete metal reduction. Interesting results were obtained also with varying the metal loadings: the lower Pt loading (1.5 wt %) achieved almost the same MF yield as the 3 wt % catalysts, which can enable the production of MF with high yields and reduced catalyst costs. Based on this study, biomass‐based renewable activated carbons can be used as catalyst supports in furfural hydrotreatment with high conversions.