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Hydrodeoxygenation of dibenzofuran and related compounds
Author(s) -
Krishnamurthy S.,
Panvelker S.,
Shah Y. T.
Publication year - 1981
Publication title -
aiche journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.958
H-Index - 167
eISSN - 1547-5905
pISSN - 0001-1541
DOI - 10.1002/aic.690270616
Subject(s) - dibenzofuran , hydrodeoxygenation , catalysis , chemistry , phenol , benzene , oxygen , photochemistry , reaction intermediate , organic chemistry , selectivity
The catalytic hydrodeoxygenation (HDO) of dibenzofuran was examined on a presulfided NiMo/γAl 2 O 3 catalyst. Based on the reaction intermediates identified in the present study a reaction network for the removal of oxygen from dibenzofuran has been established. In view of the failure to detect certain key reaction intermediates an approximate network has been proposed for kinetic analysis. Using the approximate network the effects of temperature in the range 616–649K, hydrogen pressure in the range 6.89–13.78 MPa and initial concentration of dibenzofuran in the range 9.78 × 10 −5 − 21.39 × 10 −5 g mol/g oil were examined upon the individual steps. The removal of oxygen from dibenzofuran under the above conditions proceeded via direct oxygen extrusion without hydrogenation of the adjacent benzene rings as well through the formation of hydrogenated intermediates, with the catalyst showing selectivity towards the latter mode of oxygen removal. Presulfiding the catalyst as well as addition of CS 2 , to maintain a partial pressure of H 2 S during the reaction, enhanced the activity of the catalyst. The effect of initial concentration of dibenzofuran indicated a retarding influence on its HDO, possibly due to the formation of refractory reaction intermediates. The HDO of two key reaction intermediates in the network for dibenzofuran, namely, o‐phenyl phenol and o‐cyclohexyl phenol, was also examined on a presulfided NiMo/γAl 2 O 3 catalyst to establish the reaction network for dibenzofuran. The primary mode of oxygen removal from both the phenols, in the temperature range of 561–644K and 10.34 MPa hydrogen pressure, was through the formation of highly reactive hydrogenated intermediates. All the primary reactions for o‐phenyl phenol were catalytic in nature, whereas, o‐cyclohexyl phenol was found to crack to phenol and cyclohexane even under purely thermal conditions. The rates of decomposition of the above phenols were fairly rapid and highly temperature sensitive, thereby explaining their absence in the reaction products of dibenzofuran.