Showing papers on "Pyrolysis published in 2010"

Renewable Chemical Commodity Feedstocks from Integrated Catalytic Processing of Pyrolysis Oils

Abstract: Fast pyrolysis of lignocellulosic biomass produces a renewable liquid fuel called pyrolysis oil that is the cheapest liquid fuel produced from biomass today Here we show that pyrolysis oils can be converted into industrial commodity chemical feedstocks using an integrated catalytic approach that combines hydroprocessing with zeolite catalysis The hydroprocessing increases the intrinsic hydrogen content of the pyrolysis oil, producing polyols and alcohols The zeolite catalyst then converts these hydrogenated products into light olefins and aromatic hydrocarbons in a yield as much as three times higher than that produced with the pure pyrolysis oil The yield of aromatic hydrocarbons and light olefins from the biomass conversion over zeolite is proportional to the intrinsic amount of hydrogen added to the biomass feedstock during hydroprocessing The total product yield can be adjusted depending on market values of the chemical feedstocks and the relative prices of the hydrogen and biomass

Abiotic and microbial oxidation of laboratory-produced black carbon (biochar).

Abstract: Pyrogenic or “black” carbon is a soil and sediment component that may control pollutant migration. Biochar, black carbon made intentionally by biomass pyrolysis, is increasingly discussed as a possible soil amendment to increase fertility and sequester carbon. Though thought to be extremely refractory, it must degrade at some rate. Better understanding of the rates and factors controlling its remineralization in the environment is needed. Release of CO2 was measured over 1 year from microbial and sterile incubations of biochars made from a range of biomass types and combustion conditions. Carbon release from abiotic incubations was 50−90% that of microbially inoculated incubations, and both generally decreased with increasing charring temperature. All biochars displayed log−linearly decreasing mineralization rates that, when modeled, were used to calculate 100 year C losses of 3−26% and biochar C half-lives on orders ranging from 102 to 107 years. Because biochar lability was found to be strongly controll...

Review of the stability of biochar in soils: predictability of O:C molar ratios

Abstract: Biochar is not a structured homogeneous material; rather it possesses a range of chemical structures and a heterogeneous elemental composition. This variability is based on the conditions of pyrolysis and the biomass parent material, with biochar spanning the range of various forms of black carbon. Thereby, this variability induces a broad spectrum in the observed rates of reactivity and, correspondingly, the overall chemical and microbial stability. From evaluating the current biochar and black carbon degradation studies, there is the suggestion of an overall relationship in biochar stability as a function of the molar ratio of oxygen to carbon (O:C) in the resulting black carbon. In general, a molar ratio of O:C lower than 0.2 appears to provide, at minimum, a 1000-year biochar half-life. The O:C ratio is a function of production temperature, but also accounts for other impacts (e.g., parent material and post-production conditioning/oxidation) that are not captured solely with production temperature. Th...

Immobilization of Heavy Metal Ions (CuII, CdII, NiII, and PbII) by Broiler Litter-Derived Biochars in Water and Soil

Abstract: Chars, a form of environmental black carbon resulting from incomplete burning of biomass, can immobilize organic contaminants by both surface adsorption and partitioning mechanisms. The predominance of each sorption mechanism depends upon the proportion of organic to carbonized fractions comprising the sorbent. Information is currently lacking in the effectiveness of char amendment for heavy metal immobilization in contaminated (e.g., urban and arms range) soils where several metal contaminants coexist. The present study employed sorbents of a common biomass origin (broiler litter manure) that underwent various degrees of carbonization (chars formed by pyrolysis at 350 and 700 degrees C and steam-activated analogues) for heavy metal (Cd(II), Cu(II), Ni(II), and Pb(II)) immobilization in water and soil. ATR-FTIR, (1)H NMR, and Boehm titration results suggested that higher pyrolysis temperature and activation lead to the disappearance (e.g., aliphatic -CH(2) and -CH(3)) and the formation (e.g., C-O) of certain surface functional groups, portions of which are leachable. Both in water and in soil, pH increase by the addition of basic char enhanced the immobilization of heavy metals. Heavy metal immobilization resulted in nonstoichiometric release of protons, that is, several orders of magnitude greater total metal concentration immobilized than protons released. The results suggest that with higher carbonized fractions and loading of chars, heavy metal immobilization by cation exchange becomes increasingly outweighed by other controlling factors such as the coordination by pi electrons (C=C) of carbon and precipitation.

Solution-grown silicon nanowires for lithium-ion battery anodes

Abstract: Composite electrodes composed of silicon nanowires synthesized using the supercritical fluid-liquid-solid (SFLS) method mixed with amorphous carbon or carbon nanotubes were evaluated as Li-ion battery anodes. Carbon coating of the silicon nanowires using the pyrolysis of sugar was found to be crucial for making good electronic contact to the material. Using multiwalled carbon nanotubes as the conducting additive was found to be more effective for obtaining good cycling behavior than using amorphous carbon. Reversible capacities of 1500 mAh/g were observed for 30 cycles.

Fast pyrolysis technology development

Abstract: While the intention of slow pyrolysis is to produce mainly charcoal, fast pyrolysis is meant to convert biomass to a maximum quantity of liquids (bio-oil). Both processes have in common that the biomass feedstock is densified to reduce storage space and transport costs. A comfortable, more stable and cleaner intermediate energy carrier is obtained, which is much more uniform and well defined. In this review, the principles of fast pyrolysis are discussed, and the main technologies reviewed (demo scale: fluid bed, rotating cone and vacuum pyrolysis; pilot plant: ablative and twin screw pyrolysis). Possible product applications are discussed in relation to the bio-oil properties. General mass and energy balance are provided as well, together with some remarks on the economics. Challenges for the coming years are (1) improvement of the reliability of pyrolysis reactors and processes; (2) the demonstration of the oil's utilization in boilers, engines and turbines; and (3) the development of technologies for the production of chemicals and biofuels from pyrolysis oils. One important conclusion in relation to biofuel production is that the type of oxygen functionalities (viz. as an alcohol, ketone, aldehyde, ether, or ester) in the oil should be controlled, rather then merely focusing on a reduction of just the oxygen content itself. Copyright © 2010 Society of Chemical Industry and John Wiley & Sons, Ltd

Stabilization of biomass‐derived pyrolysis oils

Abstract: BACKGROUND: Biomass is the only renewable feedstock containing carbon, and therefore the only alternative to fossil-derived crude oil derivatives. However, the main problems concerning the application of biomass for biofuels and bio-based chemicals are related to transport and handling, the limited scale of the conversion process and the competition with the food industry. To overcome such problems, an integral processing route for the conversion of (non-feed) biomass (residues) to transportation fuels is proposed. It includes a pretreatment process by fast pyrolysis, followed by upgrading to produce a crude-oil-like product, and finally co-refining in traditional refineries. RESULTS: This paper contributes to the understanding of pyrolysis oil upgrading. The processes include a thermal treatment step and/or direct hydroprocessing. At temperatures up to 250 degrees C (in the presence of H(2) and catalyst) parallel reactions take place including re-polymerization (water production), decarboxylation (limited CO(2) production) and hydrotreating. Water is produced in small quantities (approx. 10% extra), likely caused by repolymerization. This repolymerization takes place faster (order of minutes) than the hydrotreating reactions (order of tens of minutes, hours). CONCLUSIONS: In hydroprocessing of bio-oils, a pathway is followed by which pyrolysis oils are further polymerized if H(2) and/or catalyst is absent, eventually to char components, or, with H(2)/catalyst, to stabilized components that can be further upgraded. Results of the experiments suggest that specifically the cellulose-derived fraction of the oil needs to be transformed first, preferably into alcohols in a 'mild hydrogenation' step. This subsequently allows further dehydration and hydrogenation. (C) 2010 Society of Chemical Industry

Characterization of Biochars Produced from Cornstovers for Soil Amendment

Abstract: Through cation exchange capacity assay, nitrogen adsorption−desorption surface area measurements, scanning electron microscopic imaging, infrared spectra and elemental analyses, we characterized biochar materials produced from cornstover under two different pyrolysis conditions, fast pyrolysis at 450 °C and gasification at 700 °C. Our experimental results showed that the cation exchange capacity (CEC) of the fast-pyrolytic char is about twice as high as that of the gasification char as well as that of a standard soil sample. The CEC values correlate well with the increase in the ratios of the oxygen atoms to the carbon atoms (O:C ratios) in the biochar materials. The higher O:C ratio was consistent with the presence of more hydroxyl, carboxylate, and carbonyl groups in the fast pyrolysis char. These results show how control of biomass pyrolysis conditions can improve biochar properties for soil amendment and carbon sequestration. Since the CEC of the fast-pyrolytic cornstover char can be about double that...

Chemical and structural properties of carbonaceous products obtained by pyrolysis and hydrothermal carbonisation of corn stover

Abstract: The main properties of chars produced from corn stover, either by pyrolysis at 550°C (to produce biochar) or by hydrothermal carbonisation (to produce hydrochar), were studied. Carbonaceous materials were characterised by: SEM imaging, solid-state 13C NMR, FT-IR, Raman spectroscopy, and XPS. The following parameters were determined: elemental composition, cation exchange capacity, acid groups contents, BET, and yield. The hydrochar had a low ash content and low pH (4.7); recovery of C was high (57%), although only about half of the C was aromatic. Atomic O/C and H/C ratios in the hydrochar were higher than in the biochar. The same pattern was observed for the estimated concentration of carboxylic functional groups (0.07 compared with 0.04 mol/kg). The biochar had higher ash content than the hydrochar, and also higher pH (~10) (lime equivalence ~40 kg CaCO3/t). The C recovery (46%) was lower than in the hydrochar, although most of the C recovered was aromatic. Both chars could be used as soil amendments, for very different requirements. Soil responses and the residence times of the chars (especially the hydrochar) must be studied in detail to pursue long-term C sequestration.

Production of advanced biofuels: Co-processing of upgraded pyrolysis oil in standard refinery units

Abstract: One of the possible process options for the production of advanced biofuels is the co-processing of upgraded pyrolysis oil in standard refineries. The applicability of hydrodeoxygenation (HDO) was studied as a pyrolysis oil upgrading step to allow FCC co-processing. Different HDO reaction end temperatures (230–340 °C) were evaluated in a 5 L autoclave, keeping the other process conditions constant (total 290 bar, 5 wt.% Ru/C catalyst), in order to find the required oil product properties necessary for successful FCC co-processing (miscibility with FCC feed and good yield structure: little gas/coke make and good boiling range liquid yields). After HDO, the upgraded pyrolysis oil underwent phase separation resulting in an aqueous phase, some gases (mainly CO2 and CH4), and an oil phase that was further processed in a Micro-Activity Test (MAT) reactor (simulated FCC reactor). Although the oil and aqueous phase yields remained approximately constant when the HDO reaction temperature was increased, a net transfer of organic components (probably hydrodeoxygenated sugars) from the aqueous phase to the oil phase was observed, increasing the carbon recovery in the oil product (up to 70 wt.% of the carbon in pyrolysis oil). The upgraded oils were subsequently tested in a lab scale catalytic cracking unit (MAT reactor), assessing the suitability of HDO oils to be used as FCC feed. In spite of the relatively high oxygen content (from 17 to 28 wt.%, on dry basis) and the different properties of the HDO oils, they all could be successfully dissolved in and co-processed (20 wt.%) with a Long Residue, yielding near normal FCC gasoline (44–46 wt.%) and Light Cycle Oil (23–25 wt.%) products without an excessive increase of undesired coke and dry gas, as compared to the base feed only. Near oxygenate-free bio-hydrocarbons were obtained, probably via hydrogen transfer from the Long Residue. In this way, we have demonstrated on a laboratory scale that it is possible to produce hydrocarbons from ligno-cellulosic biomass via a pyrolysis oil upgrading route. The much higher coke yields obtained from the catalytic cracking of undiluted HDO oil showed the importance of co-processing using a refinery feed as a diluent and hydrogen transfer source.

Fluidic carbon precursors for formation of functional carbon under ambient pressure based on ionic liquids.

Abstract: A new strategy for the preparation of functional porous carbons is developed via direct, ambient-pressure, thermal pyrolysis of task-specific ionic liquids (ILs). The simple synthesis lies in the synergistic use of the negligible volatility of the ILs and incorporation of the crosslinkable nitrile groups in the anions. The resulting carbon materials at 800 C retain an extremely high content of nitrogen (up to 18 at%).