Organic compounds -- part of the class 532-570 series – Organic compounds – Oxygen containing
Reexamination Certificate
2001-10-01
2003-07-22
Richter, Johann (Department: 1621)
Organic compounds -- part of the class 532-570 series
Organic compounds
Oxygen containing
C568S761000, C527S400000, C162S047000, C162S071000, C162S077000
Reexamination Certificate
active
06596908
ABSTRACT:
This is the U.S. national phase under 36 U.S.C. §371 of International Application PCT/AU99/01045, filed Nov. 24, 1999.
The present invention relates to a process for the recovery of low molecular weight phenols, furfural and furfuryl alcohol and/or cellulose or cellulose-rich residues from a lignocellulosic biomass such as for example, hard or soft woods or other plant matter. In particular, the invention relates to a process for the pyrolysis-like degradation of lignocellulosic material to recover a high yield of low molecular weight phenols, furfural and furfuryl alcohol and/or cellulose or cellulose-rich residue.
Pyrolysis is a known process involving the thermal degradation of a biomass in the absence of oxygen. The process yields three product phases; a solid residue (char), pyroligneous liquor and low BTU gases. The relative yield of each phase depends on process parameters including reaction temperature, feedstock type and particle size, heat exchange method, equipment design and specification and product collection methods.
A number of methods are known for the pyrolysis of a biomass. These include batch type, ablative, vacuum, spinning disk and fluidised bed or flash pyrolysis. The main difference between these methods is the rate of heat transfer and the continuity of the process with respect to sample processing.
Hemi-celluloses are polymers of 5 carbon sugars and constitute a major component of wood. Under pyrolytic conditions at temperatures lower than that for lignin, hemicelluloses degrades into furfural, furfuryl alcohol and furans. Wood contains 10-15% of hemicellulose.
Lignin is a major component of woody material. It is a complex, high molecular weight poly phenyl propane polymer with repeating units consisting of the species guaiacol and syringol. The basic function of lignin in wood is to bind the wood cells together.
Lignin accounts for 17-40% of total wood mass. It is known that the pyrolysis of lignin yields low molecular weight phenols, in particular guaiacol and its para alkyl substituted derivatives. More recent research has demonstrated that very rapid pyrolysis of lignocellulosic material yields higher quantities of pyrolysis oil, as well as increased concentrations of phenols in the pyrolysis oil, compared with traditional batch-type techniques. The rapid pyrolysis of lignocellulosic material, combined with rapid removal of the pyrolysis products from the heat source, facilitates the production of primary pyrolysis products as secondary pyrolysis is prevented.
In practice, rapid pyrolysis is achieved via the fluidised bed system. In this system, aluminosilicate sand contained within a cylindrical reactor is heated to the pyrolysis temperature. A gas is then passed through the sand bed. The flow of gas imparts fluid like properties to the sand bed. This system is referred to as a fluidised bed reactor. Feedstock may be introduced into the fluidised bed on a separate stream of gas. Upon contact with the hot sand bed, the feedstock is pyrolysed virtually instantaneously. The movement of gas through the system transports the pyrolysis products away from the hot sand bed to various product collection systems.
At temperatures in excess of 800° C., the gas phase is the dominant pyrolysis product. Such a regime has been used to produce low BTU gases for energy production. At temperatures between 600 and 800° C. char is the major product. This material may be used for iron ore processing and as a solid fuel. Pyrolysis oil is the major product at temperatures between 350 and 600° C. and because of this most research on pyrolysis oil has been focused in this temperature region. Under conventional fast pyrolysis conditions, very little occurs below 350° C.
Oils produced by the fast pyrolysis of lignocellulosic material between 350 and 600° C. are thermally and chemically unstable and contain a large, disparate range of compounds that have proven to be very difficult to resolve. Attempts have been made to utilise these oils as a fuel for energy production. However, little success has been achieved.
There has been considerable research conducted on the fast pyrolysis of lignocellulosic material with the aim of producing phenols for adhesive purposes. At present this research has not yielded a satisfactory process. This is due to thermal and chemical instability of the product, extreme complexity of the product, inability to scale up the process, expense of the process, and instability of the process with respect to hours of continuous run.
According to one aspect of the invention, there is provided a process for the recovery of furfural and furfuryl alcohol from a lignocellulosic material comprising:
feeding a carrier gas into a reaction chamber to facilitate a fluidised bed effect and to carry reaction products and residues away from the reactor via entrainment;
introducing a feedstock comprising particulate lignocellulosic material of a predetermined particle size into the reaction chamber;
degrading the feedstock in the reaction chamber under an oxygen-containing atmosphere at a temperature of from 250° C. to 320° C.; and
quenching the degraded feedstock and carrier gas to deposit solid residues entrained in the carrier gas and to condense a liquid product comprising furfural and furfuryl alcohol.
According to another aspect of the invention there is provided a process for the recovery of low molecular weight phenols from a lignocellulosic material comprising:
feeding a carrier gas into a reaction chamber to facilitate a fluidised bed effect and to carry reaction products and residues away from the reactor via entrainment;
introducing a feedstock comprising particulate lignocellulosic material of a predetermined particle size into the reaction chamber;
degrading the feedstock in the reaction chamber under an oxygen-containing atmosphere at a temperature of from 250° C. to 320° C.; and
quenching the degraded feedstock,and carrier gas to deposit solid residues entrained in the carrier gas and to condense a liquid product comprising a phenol-rich oil.
There is also provided furfural and furfuryl alcohol and low molecular weight phenols when recovered by a process as described in the immediately preceding two paragraphs respectively.
According to a further aspect of the invention there is provided a process for the recovery of cellulose or a cellulose-rich material from a lignocellulosic material comprising:
feeding a carrier gas into a reaction chamber to facilitate a fluidised bed effect and to carry reaction products and residues away from the reactor via entrainment;
introducing a feedstock comprising particulate lignocellulosic material of a predetermined particle size into the reaction chamber;
degrading the feedstock in the reaction chamber under an oxygen-containing atmosphere at a temperature of from 250° C. to 320° C.; and
quenching the degraded feedstock and carrier gas to deposit solid residues comprising cellulose or cellulose-rich material entrained in the carrier gas.
There is further provided cellulose or cellulose-rich material recovered by a process as described in the immediately preceding paragraph.
The classical definition of pyrolysis does not allow for the presence of oxygen in the reaction atmosphere because, at normal pyrolysis temperatures, combustion would occur. However, in the present invention it has been found that the presence of oxygen in the reaction atmosphere promotes the degradation of lignin under the conditions of the invention to recover phenols as a degradation product. Further, it has been found that under these conditions the cellulose component remains substantially intact. In one embodiment, the degradation is carried out under an oxygen-enriched atmosphere.
When it is desired to produce an oil, conventional fast pyrolysis is generally conducted at a temperature of from 350 to 500° C. Under such temperatures, the rate of cellulose and lignin pyrolysis is high. As such, the resultant oil contains degradation products from both components, resulting in a complex, thermally and chemically unstable product which has prac
Butt David Arthur Edward
Hermescec Branko
Knobbe Martens Olson & Bear LLP
Richter Johann
The University of Melbourne
Witherspoon Sikarl A.
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