Butadienes from pyrolysis

Waymack, B.E. and D.S. Kellogg The effects of additives on pyrolysis of tobacco chars 54th Tobacco Science Research Conference, Program Booklet and Abstracts, Vol. 54, Paper No. 35, 2000, pp. 38-39. Waymack, B.E. and D.S. Kellogg Butadiene from pyrolysis of tobacco 55th Tobacco Science Research Conference, Program Booklet and Abstracts, Vol. 55, Paper No. 50, 2001, P- 50. 

The pattern of commercial production of 1,3-butadiene parallels the overall development of the petrochemical industry. Since its discovery via pyrolysis of various organic materials, butadiene has been manufactured from acetylene as weU as ethanol, both via butanediols (1,3- and 1,4-) as intermediates (see Acetylene-DERIVED chemicals). On a global basis, the importance of these processes has decreased substantially because of the increasing production of butadiene from petroleum sources. China and India stiU convert ethanol to butadiene using the two-step process while Poland and the former USSR use a one-step process (229,230). In the past butadiene also was produced by the dehydrogenation of / -butane and oxydehydrogenation of / -butenes. However, butadiene is now primarily produced as a by-product in the steam cracking of hydrocarbon streams to produce ethylene. Except under market dislocation situations, butadiene is almost exclusively manufactured by this process in the United States, Western Europe, and Japan. 

Significant products from a typical steam cracker are ethylene, propylene, butadiene, and pyrolysis gasoline. Typical wt % yields for butylenes from a steam cracker for different feedstocks are ethane, 0.3 propane, 1.2 50% ethane/50% propane mixture, 0.8 butane, 2.8 hill-range naphtha, 7.3 light gas oil, 4.3. A typical steam cracking plant cracks a mixture of feedstocks that results in butylenes yields of about 1% to 4%. These yields can be increased by almost 50% if cracking severity is lowered to maximize propylene production instead of ethylene. 

To recover a maximum of olefins and butadiene from recycling polyolefins, it is necessary to have a short residence time of the product gases in the fluidized bed zone to avoid no secondary reactions. The pyrolysis gas should not be circulated and used as fluidizing gas. For the experiments, steam was used as fluidizing gas [13, 14]. An easy separation of the hydrocarbon products is possible by condensation to water in a cooler. The results are shown in Table 17.6. As feedstock a light plastic fraction from household waste separation was used which contains 95.8% of PE and PP, 3% of PS, and 0.2% of PVC. 

Lebedev process. Formation of butadiene from ethanol by catalytic pyrolysis. The catalysts used are mixtures of silicates and aluminum and zinc oxides. 

Fig. 3.10. Characteristic peak-area ratio versus pyrolysis temperature for Curie-point cell. 1 and 3 = mixtures of homopolymers (polybutadiene and polystyrene) 2 and 4 = statistical copolymer of styrene and butadiene (Europrene 1500). 1 and 2 = ratio of peak areas of styrene and vinylcyclohexane 3 and 4 = ratio of peak areas of styrene and butadiene. From ref. 108.

The major degradation product of natural rubber is l-methyl-4-(l-methylethenyl)cyclo hexene. The presence of this compound as the major degradation product along with 2-methyl-1,3-butadiene (monomer) and groups of compounds containing 15 and 20 carbon atoms (three and four monomer units) in the pyrolysate of a rubber is sufficient to identify it as natural rubber. Similarly, the presence of l-chloro-4-(l-chloroethenyl)cyclohexene and 2-chloro-l, 3-butadiene, the cyclic dimer and monomer of poly(chloroprene) rubber, in the pyrolysate of a rubber identify it as poly(chloroprene) rubber. A correlation between the crosslink density and the product ratio of isoprene dimer species to isoprene formed from pyrolysis of natural rubber vulcanisates has been reported 697436 [a.232]. The major products of the isoprene dimer species were l,4-dimethyl-4-vinylcyclohexene and... 

On the basis of laboratory work of Morell and co-workers, a pilot plant was set up for further study of the pyrolysis step. Results are reported by Schniepp, Dunning, Geller, Morell, and Lathrop (115). The equipment consisted essentially of a metal pyrolysis coil in a bath of molten lead for the main step of the process. Vapors from the coil were cooled rapidly in a quench chamber and passed through a packed column where acetic acid and other liquid pyrolysis products were washed out. The butadiene gas was scrubbed, dried, compressed, and finally condensed to liquid for collection and weighing. It is interesting at this point to note the pilot plant recoveries tabulated by Schniepp and co-workers. These are given below as over-all recoveries of butadiene from the glycol. 

By-products from EDC pyrolysis typically include acetjiene, ethylene, methyl chloride, ethyl chloride, 1,3-butadiene, vinylacetylene, benzene, chloroprene, vinyUdene chloride, 1,1-dichloroethane, chloroform, carbon tetrachloride, 1,1,1-trichloroethane [71-55-6] and other chlorinated hydrocarbons (78). Most of these impurities remain with the unconverted EDC, and are subsequendy removed in EDC purification as light and heavy ends. The lightest compounds, ethylene and acetylene, are taken off with the HCl and end up in the oxychlorination reactor feed. The acetylene can be selectively hydrogenated to ethylene. The compounds that have boiling points near that of vinyl chloride, ie, methyl chloride and 1,3-butadiene, will codistiU with the vinyl chloride product. Chlorine or carbon tetrachloride addition to the pyrolysis reactor feed has been used to suppress methyl chloride formation, whereas 1,3-butadiene, which interferes with PVC polymerization, can be removed by treatment with chlorine or HCl, or by selective hydrogenation. 

Buta-1,3-diene, 1 -(2 -furyl)-pyrolysis, 4, 600 Buta-1,3-diene, 1-mercapto-thiophenes from, 4, 887 Buta-1,3-diene, 1 -(1 -methyl-2-pyrrolyl)-thermal cyclization, 4, 285 Buta-1,3-diene, l-(2-thienyl)-electrocyclization, 4, 748 Butadienes... 

Isolable pyrazolines (183) are obtained from the (1,3-butadiene)phosphonic acid esters (182 X=S02Me, COOalkyl R "=H or Me R2=Me or Ph) (products from (182 X=CN) are thermo-labile) and diazomethane. Pyrolysis of the phosphorylated pyrazolines affords phosphonopentadienes rather than phosphono-cyclopropanes (contrast (184)) and with NaH give pyrazoles or pyrazolephbsphonic acid esters. 

Levin, B.C., A summary of the NBS litterature Reviews on the chemical nature and toxicity of the pyrolysis and combustion from seven plastics acrylonitrite-butadien-styrenes (ABS), nylons, polyesters, polyetylenes, polysterenes, poly(vinyl-chlorides) and rigid polyurethane foams, KB SIR 85-3267, 1986... 

The first total synthesis of D/E-trans annellated yohimbines, e.g., ( )-yohim-bine (74) and ( )-pseudoyohimbine (88), was published in preliminary form by van Tamelen and co-workers (218) in 1958, while full details (219) appeared only in 1969. Key building block 393, prepared from butadiene and p-quinone, was condensed with tryptamine, yielding unsaturated amide 394, which was subsequently transformed to dialdehyde derivative 396. Cyclization of the latter resulted in pseudoyohimbane 397. Final substitution of ring E was achieved via pyrolysis, oxidation, and esterification steps. As a result of the reaction sequence, ( )-pseudoyohimbine was obtained, from which ( )-yohimbine could be prepared via C-3 epimerization. 

The unsubstituted spirononadiene has been obtained from silicon atoms and the diene, albeit in low yield. However it results in better yield from methoxytris(trimethylsilyl)silane and the diene on photolysis. a-Elimination is non-specific but favours the methoxysilylene, addition giving the two silacyclopentenes (111) and (112) with buta-1,3-diene (Scheme 186). Pyrolysis with excess butadiene gives the spiro derivative, in support of the cyclosilylene intermediate (113 Scheme 187) (81JA7344). 

Isoprene (melting point -146°C, boiling point 34°C, density 0.6810) may be produced by the dehydrogenation of iso-pentane in the same plant used for the production of butadiene. However, the presence of 1,3-pentadiene (for which there is very little market) requires a purification step. One method produces isoprene from propylene. Thus, dimerization of propylene to 2-methyl-1-pentene is followed by isomerization of the 2-methyl-1-pentene to 2-methyl-2-pentene, which upon pyrolysis gives isoprene and methane. 

In all examples of the palladium-catalyzed telomerization discussed up till now, the nucleophile (telogen) can be considered renewable. The taxogens used (butadiene, isoprene), however, are still obtained from petrochemical resources, although butadiene could, in principle, also be obtained from renewable resources via the Lebedev process that converts (bio)-ethanol into 1,3-butadiene. Limited attention has been given in this respect to the great family of terpenes, as they provide direct access to renewable dienes for telomerization. In particular, those terpenes industrially available, which are derived mostly from turpentine, form an attractive group of substrates. Behr et al. recently used the renewable 1,3-diene myrcene in the telomerization with diethylamine, for instance [18]. The monoterpene myrcene is easily obtained from (3-pinene, sourced from the crude resin of pines, by pyrolysis, and is currently already used in many different applications. 

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