Production of wood pyrolysis

Suida An extractive distillation process for concentrating the dilute acetic acid obtained from the manufacture of cellulose acetate. It was originally used for separating the products of wood pyrolysis. Invented in 1926 by H. Suida in Vienna and operated in the 1930s. 

TABLE 33.6 Modes of Pyrolysis and Typical Products of Wood Pyrolysis... 

Products of wood pyrolysis Without catalyst H2SO, 3.0% 5,0% ZnCb 1.4% Engine oil refinery acid tar 5% 9% 17% ... 

As an example, let s examine the industrial polyazeotropic mixture, which is a by-product of wood pyrolysis (Petlyuk, Kievskii, Serahmov, 1979). Approximate composition of this mixture and components boiling temperatures are given in Table 3.1. BoiUng temperatures and compositions of azeotropes are given in Table 3.2. The structural matrix shown at Fig. 3.20 was synthesized for this mixture. 

Let s return to the example of industrial mixture that is a by-product of wood pyrolysis. It is seen from the examination of product simplex Regsmp = 1 234 23 38 568 58 78 89 8 that in a column sequence consisting of... 

The pyrolysis products of wood can be broadly grouped into three categories as shown in Scheme 3, i,e., the combustible... 

TABLE VII. PYROLYSIS PRODUCTS OF WOOD AND TREATED WOOD AT 600°... 

Himmelblau D. A. and Grozdits G.A. (1999) Production of Wood Composite Adhesives with Air-Blown, Fluidized-Bed Pyrolysis Oil. In International Contributions to Wood Adhesion Research, Forest Products Society, Madison, WI. 

The results presented here show the general trend if chloro-organic compounds are present in the feedstock. The amount of chloro-organics in the feedstock used here were somewhat unrealistic but selected to better understand and measure PCDD/F formation and concentration in the products of fast pyrolysis. In reality, there are no mono-fractions of wood contaminated only with chloro-organic compounds, Generally, pyrolysis of waste wood mixtures results in a much less contaminated oil as presented in this study. However, further investigations are necessary to prove if de novo synthesis takes place during fast pyrolysis of contaminated waste wood. 

Catalysts of wood pyrolysis are used to increase the yield of charcoal and to obtain a charcoal with modified properties or to produce definite valuable volatile products. The substances promoting condensation reactions are employed if high jields of charcoal are desired (4, 5, 7). Some catalysts increase the apparent density of charcoal, the pore dimensions and their adsorbency nature. Of all silvichemicals charcoal is currenUy the most in demand Commercial interest is focused on deciduous wood charcoal or charcoal briquettes. 

Spince B. Zhurinsh A. Zandersons J. (1998) Chemical analysis of wood pyrolysis liquid products. Latvian Chemical Journal, 3, 92-5. (in Latvian)... 

Table IV. Pyrolysis Products of Wood and Treated Wood...

Experiments were conducted on the pyrolysis products of wood samples to affirm that the increased amounts of char involved a decrease in the amount of combustible tars (52). The chemicals increased the yield of char, water, and noncondensable gases at the expense of the flammable tar fraction. These results confirmed that the increased amount of residual char in TG results was associated with the reduction of the combustible volatiles. 

Cellulose pyrolysis has been studied in detail from a variety of points of view mainly related to chemical utilization of wood pyrolysis products or to fire related problems. Analytical pyrolysis of cellulose is not often used as a tool for cellulose detection, but it is a common procedure for studying the pyrolysis products. A variety of analytical procedures have been applied for this study, pyrolysis/gas chromatography/mass spectrometry (Py-GC/MS) being the most common [11-16]. Besides Py-GC/MS, other analytical procedures also have been utilized, such as Py-MS [17,18], Py-IR [19], and off-line Py followed by HPLC [20]. The Py-MS spectrum of cellulose was shown in Figure 5.4.1 (B). Some procedures applied GC/MS on derivatized pyrolysis products (off-line), the derivatization being done by silylation [21], permethylation, perbenzoylation [22], etc. Information about cellulose also has been obtained from the analysis of pyrolysis products of several cellulose derivatives, such as O-substituted cellulose [23]. Also the study of cellulose crystalline structure with X-ray during pyrolysis has been used [23a] to generate information about the pyrolysis mechanism. 

The principle of wood pyrolysis is shown in Eigure 3.39. The resulting products are smoke and/or charcoal. 

A typical Py-GC-MS trace from a wood sample (Figure 9) contains 50-100 individual peaks corresponding to at least that many products. The individual pyrolysis products include fiirans plus a variety of carbonyl compounds that are typical of polysaccharides, particularly cellulose and hemi-cellulose (42). In addition, many different lignin-derived phenols are obtained that, like the CuO reaction products, retain the methoxylation pattern of the parent structural units and carry diagenetic information on their side chains (43). Characteristic pyrolysis products of wood extractives such as resin acids also can be detected (44) thus, this analytical method is... 

Production of Wood Pvrolvsis Liquids. Sawdust (primarily pine and fir) pyrolysis was carried out in a fixed bed reactor, which held about 200 ml of sample. The sawdust charge had the following elemental analysis (dry basis) 0 - 49.205S, H - 6.80J5, 0 - 43.40%, ash -0.60%. The reaction was conducted at atmospheric pressure by heating the sample at approximately 20 C/min. to 520 0 in helium flowing at about 800 ml/min. The sample was then held at the final temperature for three hours with helium gas flowing. 

This screening approach is not a stand-alone technique, however, and bench-scale experimentation is needed to provide data for parameters which the screening approach does not adequately address isolation and confirmation of isomers of products, product mass balance, long-term studies in accessing catalyst life, and the variation of certain reactor operating conditions which have limited ranges at this scale, such as feed partial pressure. The catalytic conversion of wood pyrolysis products will be discussed in a screening context in this paper. 

The use of MBMS for real time screening of wood pyrolysis product conversion over Mobil s HZSM-5 allows the rapid, qualitative evaluation of performance of different catalysts, reaction conditions and feedstocks. This information can help guide more extensive testing at the bench-scale level and provide insight into the chemistry of conversion. The following conclusions can be drawn from the work to date ... 

Trajectories of Distillation in Infinite Columns Under Infinite Reflux Table 3.1. Composition of wood pyrolysis product... 

Figure 3.20. A structural matrix and one connection chain 1 234 23 38 568 58 78 89 8 of wood pyrolysis product.

Acetone was originally observed about 1595 as a product of the distillation of sugar of lead (lead acetate). In the nineteenth century it was obtained by the destmctive distillation of metal acetates, wood, and carbohydrates with lime, and pyrolysis of citric acid. Its composition was determined by Liebig and Dumas in 1832. 

Slow pyrolysis, also called carbonization, is characterized by a high charcoal yield and is not considered for hydrogen production processes. The slow pyrolysis of wood (24 h typical residence time) was a common industrial technology to produce charcoal, acetic acid, methanol, and ethanol from wood until the early 1900s. 

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