Wood pyrolysis oils, chemical

This paper discusses the preliminary engineering data leading to the construction of a vacuum pyrolysis pilot plant for the conversion of wood into oils, chemicals and charcoal. 

Chemical Characterization of Wood Pyrolysis Oils Obtained in a Vacuum-Pyrolysis Multiple-Hearth Reactor... 

Fast pyrolysis oil has almost the same elemental composition as the biomass itself hence it can be seen as a kind of liquid wood. It can be transported, can be pressurized and processed more easily than solid biomass. One of the major difficulties in the catalytic conversion of solid biomass is achieving effident con-tad between the heterogeneous catalyst (which is most of the times a solid) and the biomass itself. In this context, bio-oil provides more options for easier catalytic conversion. However, pyrolysis is a very complex and the oil is a difficult to handle chemical mixture. Complete vaporization, for instance, is not possible because part of the components start to decompose and polymerize upon heating... 

Pyrolysis oil (bio-oil) is produced in fast and flash pyrolysis processes and can be used for indirect co-firing for power production in conventional power plants and potentially as a high energy density intermediate for the final production of chemicals and/or transportation fuels. Gas chromatographic analysis of the liqtrid fraction of pyrolysis products from beech wood is given in Table 3.6 (Demirbas, 2007). Biocmde resrrlts from severe hydrothermal upgrading (HTU) of relatively wet biomass and potentially can be used for the production of materials, chemicals,... 

The main conclusions of the Round Robin were Karl-Fischer titration is recommended for analysing water in pyrolysis oils. Solids content as ethanol insolubles is accurate for white wood oils but a more powerful solvent, like a mixture of methanol and methylene chloride (1 1) is needed for extractive-rich oils. For the elemental analysis at least triplicates are recommended. Kinematic viscosity is an accurate method for pyrolysis oils. Stability index needs more clarification and testing,- Results of chemical characterisation were not very consistent. It may be necessary to prepare standard solutions with known aniounts of conqiounds for... 

Liquid fuels producible by thermal conversion of biomass include fuel oil, pyrolysis oils, methanol (discussed under chemicals production), and others. This section discusses the production of fuel oils and pyrolysis oils from wood. 

Laboratory (4) and Process Development Unit (5,6) studies originally conducted at the Universite de Sherbrooke, and now conducted jointly with the private industry at Universite Laval, province of Quebec, have led to the conclusion that thermal decomposition under reduced pressure is an attractive approach for the conversion of biomass into chemicals and fuels products. The process uses a multiple-hearth furnace for wood pyrolysis. This approach is characterized by a low pressure and a short residence time of the vapor products in the rciactor. When compared with conventional, atmospheric pressure carbonization, vacuum pyrolysis has the potential to significantly enhance the yields of organic liquid products with respect to solid and gaseous products. The pyrolysis oils (biooils) obtained from this process can be deoxygenated into transportation fuels upon further upgrading (7). Specialty as well as commodity (Pakdel, H. Roy, C. Biomass, in press) chemicals can also be extracted from the pyrolysis oil product. 

However, few details of the chemical nature of the pyrolytic oils produced from wood or other biomass have been reported. Some recent studies of the composition of pyrolysis oils obtained from poplar wood were carried out by workers of the Pacific Northwest Laboratories of Battelle Institute [7] and the Universite de Sherbrooke [8]. Methods of quantitative determination of functional groups in the pyrolytic oils from wood were tested in our laboratory by Nicolaides [9]. However, more detailed characterisation exists in the literature for the products of the thermal degradation of cellulose [10,11,12,13,14]. 

The identification and extraction of valuable chemicals from wood-derived oils is a very important goal for the biomass thermochemical conversion industry (lz2). Pyrolysis oils have been extensively studied and extensive number of compounds have been identified (3-4). However to our knowledge there are only two general methods which have been reported for the fractionation of pyrolysis oils... 

Extensive works conducted by different authors utilizing GC and GC/MS sometimes lead to different results which indicate tfui difficulties of carrying out accurate detailed analysis of the chemical constitupyrolysis oils. Examples of incomplete or even contradictory results can be found in the literature (3 4) and this paper in the analysis of vacuum pyrolysis oils. Other researchers have studied the functional group distribution in l>yrolysis oil (8), Althoiigh those techniques are long and tedious, they will lead to useful information about wood oil chemistry. 

Evans RJ, Milne T. 1988. Molecular-beam, mass-spectrometric studies of wood vapor and model compounds over an HZSM-5 catalyst. In Soltes EJ, Milne TA (editors). Pyrolysis Oils from Biomass. American Chemical Society Symposium Series 376. American Chemical Society. 

Gagnon J, Kaliaguine S. 1988. Catalytic hydrotreatment of vacuum pyrolysis oils from wood. Industrial Engineering and Chemical Research 27 1783-1788. 

Fast pyrolysis utilizes biomass to produce a product that is used both as an energy source and a feedstock for chemical production. Considerable efforts have been made to convert wood biomass to hquid fuels and chemicals since the oil cri-... 

Terpenes are obtained either by processing wood in the kraft process in paper production or by collecting resins and turpentine from conifers. The scale of produced terpenoids in comparison with fats and oils is small. Applications for terpenes are in pure form as solvents, as odorous substances, or in dyes. Most terpenoids contain double bonds which are readily available to perform chemical reactions. A widespread component of turpentine is a-pinene, from which many fragrances are produced. A further often-used resource is myrcene, which is obtained by pyrolysis of (3-pinene. Myrcene is an important base chemical to produce, for example, the fragrances nerol and geraniol [7]. 

Autio J, Lehto J, Heikkinen M, et al. Production of bio-oil and chemicals in an integrated pyrolysis pilot unit. In Proceedings of the Third Nordic Wood Biorefinery Conference. March 22-24, 2011, Stockholm, Sweden. Innventia AB, p. 47-52. 

In the traditional "wood distillation industry" hardwood was preferred for production of chemicals. Hardwood distillation was formerly an important source for production of acetic acid, methanol, and acetone which were the primary products of this process. The heat required for pyrolysis was generated by burning gas, oil, or coal. In the thermal degradation of wood the volatile components are distillable and can be recovered as liquids after condensation (Fig. 10-2). The solid residue, charcoal, is mainly composed of carbon. At higher temperatures the carbon content is increased because of a more complete dehydration and removal of volatile degradation products. Charcoal is mainly used as combustible material for special purposes. A number of charcoal products are known, including activated carbon for adsorption purposes. 

As German regulations favor materials recycling over simple heat production, fast pyrolysis, which gives a liquid (bio oil) as main product, is getting more and more attention, because bio oil can also be used as a source for chemicals (2). On the other hand, fast pyrolysis has to compete with existing alternatives such as combustion and gasification. Therefore, the quality of the oil from pyrolysis of contaminated waste wood is of paramount importance, if this process is to be considered an attractive alternative approach for costumers such as disposal site operators or waste wood collection sites. 

Thermal cracking of ethane, propane, butane, naphthas, gas oils, and/or vacuum gas oils is the main process employed for the production of ethylene and propylene butadiene and benzene, toluene, and xylenes (BTX) are also produced. Thermal cracking of these hydrocarbons is also called pyrolysis of hydrocarbons. Ethylene is the organic chemical produced worldwide in the largest amoimts and has been called keystone to the petrochemical industry. This technology is well documented in the literature. Somewhat similar thermal cracking processes are used to produce vinyl chloride monomer (VCM) from ethylene dichloride (EDQ, styrene from ethylbenzene, and allyl chloride from propylene dichloride (PDC). Production of charcoal and coke from wood and coal is actually a pyrolysis process, but it is not discussed here. 

DeGroot, W.F. Pan, W-P. Rahman, M.D. Richards, G.N. "Esurly products of pyrolysis of wood." In Production. Analysis and Upgrading of Oils from Biomass. Vorres, K.S., Ed., American Chemical Society, Division of Fuel Chemistry Abstracts, 1987, 32(2). 36. 

Pakdel, H. Roy, C. "Chemical characterization of wood oils obtained in a vacuum pyrolysis multiple hearth reactor." In This Volume. 

The sequential elution chromatographic technique has been found particularly helpful in separating whole oil produced by vacuum pyrolysis of wood into chemically distinguishable fractions. More than 30 of the P.C.U. oil that eluted first (FI to Fll) could bo analysed by GC and GC-M.S with less unambiguity. 

The pyrolysis products of vegetable oils and wood are highly dependent on the chemical composition of the raw material, and the elemental composition of biofuels typically resembles that of biomass. One possibility is to apply fast pyrolysis to these raw materials directly or after their alkaline hydrolysis for manufacturing liquid fuels (mainly biodiesel).An interesting approach is also the direct pyrolysis of the CTO soap for producing biofuel. In this process concept, sodium could also be recovered simultaneously in the form of Na2C03, thus eliminating, for example, the... 

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