Catalytic and non-catalytic flow-pyrolysis of bibenzyl. Possible homolytic and heterolytic processes on basic CaO

Pyrolysis behaviors of two coal-related model compounds on a fixed-bed reactor

“…Therefore, it is thought that, for the initial steps, the homolytic scission of the C aliphatic -C aliphatic bond (step 1) is the primary step during the pyrolysis of BB. The previous study [8] found that toluene is the primary product when no catalyst was used, while trans-stilbene is the primary product when CaO was used as catalyst. However, in this study, the yield of trans-stilbene and phenanthrene is more than that of toluene, suggesting that the direct dehydrogenation of BB to produce trans-stilbene, not through radical reaction, may also exist under these experiment conditions.…”

“…Because there are no hydrogen radical donors to stabilize these initial radicals, the initial produced radicals P 1 , P 2 and P 3 need to be stabilized through hydrogen abstraction from BB (step 4). The hydrogen abstraction would produce benzene, toluene, ethylbenzene and an important intermediate radical P 4 [8,10]. Two major liquid products, trans-stilbene (P 5 ) and phenanthrene (P 7 ), are generated from dehydrogenation and cyclization of P 4 [31].…”

“…Thermolysis of BB in gas and liquid phases has been extensively investigated [5][6][7][8], and the results have been reviewed by Marvin L. Poutsma [9]. It is generally accepted that the homolytic cleavage of C aliphatic -C aliphatic bond to form benzyl radicals is the primary process, and toluene was the primary product when there was no catalyst, while stilbene was the primary product when CaO was used as catalyst [8]. When BB was immobilized on a silica surface, the pyrolysis pathway was influenced by diffusional constraints.…”

A theoretical study on bond dissociation enthalpies of coal based model compounds

“…Many experimental and theoretical studies on model compounds have been carried out, including aromatic hydrocarbon compounds [11][12][13][14][15][16][17][18][19][20][21][22][23], ethers compounds (aromatic ethers [24][25][26][27][28][29][30][31] and ester ethers [32,33]), carboxylic acids [34], and heterocyclic aromatic compounds [35][36][37][38] bond dissociation enthalpies (BDE) of the oxygen-carbon and carbon-carbon bonds in substituted phenethyl phenyl ethers (PPEs) which representing the dominant b-O-4 ether linkage [28], and C a AO and C a AC b BDEs for a series of b-5 arylcoumaran [29]. They also examined the substituent effects on these bond dissociation enthalpies.…”

Study on the Catalytic Pyrolysis Mechanism of Lignite by Using Extracts as Model Compounds

“…An attractive way to study the catalytic pyrolysis mechanism of lignite is to use model compounds. Sekiguchi et al [12] studied the effect of basic CaO on the pyrolysis of bibenzyl, and it was found that toluene was the primary product with the catalyst while stilbene was the primary product without the catalyst. Wang et al [13] performed a theoretical study on the catalytic pyrolysis of benzoic acid with or without four different metallic oxides using the periodic density functional theory (DFT) calculation.…”