The hydrogenolysis of glycerol to lower alcohols.
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Date
2010
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Abstract
Much work has been done towards the hydrogenolysis of glycerol to 1,2-PDO and 1,3-PDO
using various heterogeneous systems including Rh, Ru, Pt, PtRu, copper systems and Raney
Ni in batch systems. However, routes to lower alcohols, such as 1-propanol and ethanol have
been less discussed. From an industry point of view, the production of lower alcohols, such as
propanol and ethanol, is very interesting.
Different ruthenium, palladium and platinum catalysts were employed to study the effect of
the support on the catalytic performance in batch mode. These catalysts were evaluated for
their production of lower alcohols, especially 1-propanol using concentrated glycerol
solutions. Among the other solid acids tested in combination with Ru/C, Amberlyst DT gave
the most promising results from a 1-PO point of view, achieving a 34.9 mol% glycerol
conversion with a selectivity of 38 mol% selectivity to 1-propanol. Despite the low glycerol
conversion (1.3 mol%), Pd/C gave a promising 1-PO selectivity (> 85 mol%).
The use of supported Ni catalysts, an inexpensive system, towards the chemical
transformation of glycerol to lower alcohols, has appeared less frequently in the literature.
The activity of Ni supported catalysts on silica and alumina was studied for the
transformation of glycerol to lower alcohols, primarily 1-propanol and ethanol in a fixed bed
continuous flow reactor. Several characterisation techniques were performed on the fresh and
used catalyst, such as BET, XRD, TPD, TPR, TGA and electron microscopy.
The objective was also to continue the development of a more detailed mechanistic
understanding of the formation of lower alcohols from glycerol. In an endeavour to
understand the process better, the role of proposed intermediates, 1,2-propanediol, 1,3-
propanediol, ethylene glycol and ethanol was investigated, as well as the influence of the
hydrogen partial pressure. Under the reaction conditions employed, it was clear that the
hydrogenolysis of C-C and C-O bonds of glycerol took place to a lesser extent when
compared to dehydrogenation and dehydration which are seen as the dominating initial steps.
Ethanol was produced in high selectivities with 1,2-propanediol as feed and 1-propanol was
the main product obtained when 1,3-propanediol was used as feed.
Description
Thesis (Ph.D.)-University of KwaZulu-Natal, Westville, 2010.
Keywords
Hydrogenolysis., Glycerin., Alcohols., Theses--Chemistry.