FR2529904A1 - Process for hydrogenolysis of matter of lignocellulosic origin - Google Patents

Abstract

Process for hydrogenolysis by the action of hydrogen at atmospheric pressure on a suspension of lignocellulosic matter in a solution of ethylanthraquinone in a heavy alcohol.

Description

 The present brunet describes a process for the hydrogenolysis of lignocellulosic materials consisting essentially of treating, with a gas containing hydrogen at pressure close to the atmosphere, the said previously dried materials and / ml roasted, fragmented and / or ground, and suspended in an organic liquid consisting of a heavy alcohol and an anthraquinone derivative.

 It is known to carry out the hydroliquefaction of lignocellulosic materials by energetic treatments such as for example the application of hydrogen under a pressure of 300 bars at a temperature of 300 to 4000 ° C. on a suspension of said materials in a hydrocarbon. The industrial transposition of such processes proves difficult, if not impossible, because of the extreme operating conditions proposed. The continuous implementation of such treatments imposes the solution to the problem of the continuous introduction and extraction of raw materials and finished products. No material today allows to solve them. difficulties in transferring materials as heterogeneous as lignoceilulosic derivatives from the outside to the inside of a reaction vessel operating at 300 bars.

 The applicant has discovered a hydrogenating reaction mixture which makes it possible to obtain a hydrogen analysis of lignocellulosic materials under accessible operating conditions, in particular not requiring the application of pressures different from those of ambient.

 The fundamental principle to which the process according to the invention applies consists in the discovery that ethylhydroanthraquinone, in solution in an appropriate solvent, liberates its hydrogen on contact with a lignocellulosic material such as wood and that its corresponding hydrogenation maintains a balance permanent between this product and its oxidized counterpart - ethyl- anthraquinone.

 We now describe the different stages of the process as it appears in Figure 1. We assume that the raw material consists of wood in the form of wood chips or paper mills of conventional dimensions. Other lignocellulosic materials can be used such as straw, rice hulls, bark, fruit kernels, and in general any lignocellulosic material which is renewed annually. On the other hand are excluded from the scope of the process, fossil wood products such as lignite, peat, coal or even natural charred woody materials.

 On the other hand, the applicant has found that roasted lignocellulosic materials, in particular by applying one of the methods described in French patents Nos. 81.16.463 and No. 80.06.044 are particularly suitable and appear even superior to the same raw materials or simply dried. The main reason is that the roasted materials lend themselves to easy grinding, making it possible to reduce it to great finesse, thus facilitating their reaction ability in the liquid medium.

 The raw wood chips are introduced into the dryer (1) or by any known means, their residual water is eliminated to a content less than or equal to 10 Ó and preferably less than 5 m.

 They are then treated by roasting (2) by one of the aforementioned processes at a temperature in the region of 2500 C. The gases obtained from roasting are recovered and recovered by their content of acetic acid.

 The roasted wafers are subjected to grinding by all. known means in the apparatus (3) which can be for example a hammer mill, a ball mill or a disc mill. It is also in accordance with the invention to grind plates mixed beforehand with the reaction organic liquid. This is particularly advantageous for the use of disc mills then achieving a very fine suspension fineness. As a general rule, the particular dimension of the ground product is around 80 microns or below.

 The hydrogenolysis is carried out in the enclosure (4) into which is introduced said reaction organic liquid liquid carrying in suspension the lignosulphosic material ground in a proportion of between 1 part of solid for 2 to 15 parts of liquid and preferably in a proportion of the order of 1 part of solid for 10 parts of liquid.

The reaction liquid consists of a solution of ethylanthraquinone in a heavy alcohol of OXO type C13 - C15
The reducing gas consists of hydrogen or a gas mixture containing at least 10% of hydrogen. This gas is admitted into the reactor so as to make suitable gas / suspension contact, either by simple bubbling, or by diffusion methods usually carried out in any gas-liquid reactor. The reaction pressure is close to atmospheric pressure but can take values slightly higher insofar as ctsci does not cause any particular technological difficulty. The temperature is maintained by all known means between 240 and 300 ° C. and preferably around 2800 C. The reaction time is a function of the gas flow rate and the fineness of the solid in suspension. Thus, for a solid less than 80 microns and a hydrogen flow rate of 500 lZh per kg of dry wood, the reaction time is approximately 3 hours.

 The conversion rate expressed as the percentage of starting material transformed into liquid or gas increases with the reaction time to reach and even exceed 95 m. If we take into account the ash present at the start in the raw material, the conversion rate reveals a quasi-quantitative transformation of the original lignocellulosic molecules.

 These are transformed into more or less oxygenated hydrocarbon compounds, of molecular weight sufficiently low to be continuously entrained outside the reactor and can be immediately fractionated in a suitable apparatus (6). The fractions obtained can be used either as a substitutable fuel for petroleum hydrocarbons, or as synthetic organic compounds in the chemical industry.

 The solvent consumption remains low because the reaction mixture can itself be recycled continuously as indicated in FIG. 1. A simple means of recovering the catalyst consists in its oxidation in air followed by cooling. The oxidized compound, namely ethylanthraquinone, is practically insoluble when cold in the heavy alcohol used as opposed to the solubility of the reduced derivative, ethylhydroanthraquinone, or even of the same product oxidized in the mixture at 2500C.

The weight balance of the operation appears as oozing for 100; 9 of air-dried wood (15 Ó of humidity)
Solid residue (including ash) 1 to 5 Ó
Liquid 80 to 90 Q
Gas 10 to 15
On liquid, soluble in THF = 95 Ó including 25 Ó distilling at 1500C (under 1 atm).

EXAMPLE
3
1000 cm of an organic mixture containing, by weight, 90 tD of acropol 35 and 10% of ethylanthraquinone are introduced into a stirred reactor.
To this mixture is added a previously dried sawdust, of average particle size equal to mu, in proportion such that the volume occupied by the wood is substantially equal to half that of the organic phase. This reactor is swept by a stream of hydrogen of 50 l / h. The medium is brought fairly quickly (about 1 hour) to a temperature of 2500C and then gradually over three hours from 2500C to 3000C.

 At the end of this reaction, a hydrogenolysis product of the wood soluble at 95 m in tetrahydrofuran corresponding to 84: 0 by weight of the treated wood is collected. The amount of unprocessed wood is 3 S.

Claims (4)

 1 - Process for the hydrogenolysis of a lignocellulosic material consisting  to mix part of said material with one to ten parts of a  heavy alcohol containing in solution from ten to fifty percent by weight  ethylanthraquinone and Xor ethylhydroanthraquinone, to heat  the said mixture at a temperature between 2400C and 3000C, and  put it in contact with a gas containing hydrogen at a pressure  close to atmospheric pressure, for a period such that the  quantity of hydrogen involved corresponds to at least ten percent in  weight of lignocellulosic raw material.  in C13 - C15. 2. Method according to 1 in which the heavy alcohol is an alcohol of the OXO type  previously roasted before its fragmentation, 4. Liquid hydrocarbon product obtained by one of the processes described above. 3. Method according to 1 and / or 2 in which the lignocellulosic material is Figure 1 legend 1 - Drying 2 - Roasting. Energy concentration and product standardization 3 - Crushing. Below 80 microns. 4 - Catalytic hydroliquefaction 5 - Distillation. Recovery: light fraction, heavy fraction, solvent 6 - Crystallization. Recovery: catalyst A - Forest or paper-type plates B - Roasting juice C - High temperature gasification. Hydrogen production D - Catalyst recycling E - Solvent recycling F - Recovery of the light fraction G - Recovery of the heavy fraction x - Roasted wood towards gasification X - Roasted wood towards hydroliquefaction