Fuel and Chemicals from Renewable Alcohols: Part 1+2

The present work entitled Fuel and Chemicals from Renewable Alcohols covers the idea of developing routes for producing sustainable fuel and chemicals from biomass resources. Some renewable alcohols are already readily available from biomass in significant amounts and thus the potential for these renewable alcohols, together with other primary renewable building blocks, has been highlighted in the introductory chapter.

While the first chapter covers the general potential of a renewable chemical industry, the other chapters deal with particular possibilities. It is shown how ethanol and glycerol can be converted into hydrogen by steam reforming over nickel or ruthenium based catalysts. This process could be important in a future hydrogen society, where hydrogen can be utilized in high efficiency fuel cells.

Hydrogen produced from biofeedstocks can also be used directly in the chemical industry, where it can compete with hydrogen production from natural gas. Similar substitution possibilities are emerging in the case of conversion of renewable alcohols to synthesis gas, which is used for instance in the manufacture of methanol and synthetic fuel.

Here it is illustrated how glycerol can be converted directly to diesel fuel in a one pot reaction consisting of: conversion of glycerol to synthesis gas over a Pt-Re/C catalyst followed by conversion of the produced synthesis gas to liquid hydrocarbons by Fischer-Tropsch synthesis using a Ru/TiO2 catalyst.

Oxidation of aqueous solutions of ethanol over gold catalysts with air as oxidant yields acetic acid selectively. This process is perhaps one of the most promising ways of utilizing cheap renewable alcohol to produce high value chemicals. Moreover, the process will most likely be able to compete economically with existing process routes to acetic acid, and it is significantly more environmentally friendly.

A final type of reactions examined in this thesis is the dehydration of different renewable alcohols over solid acid catalysts to yield olefins or aromatic compounds. It is shown that ethanol can be dehydrated into ethylene with high selectivity at temperatures below 200 °C. This reaction also seems to have potential for competing with the present non-catalytic production of ethylene from steam cracking of naphtha carried out at temperatures around 800 °C.

The price of ethylene is about twice that of fuel grade bioethanol, and this reaction is another example of a possible production of value-added chemicals from renewable resources. High temperature dehydration of methanol and ethanol results in a range of different hydrocarbons, which can be used either as gasoline fuel or, by altering process conditions, as a way to produce important olefin products which can be used in the manufacture of plastics etc.