GB2175599A - Process for obtaining liquid products from solid carbonaceous materials - Google Patents

Abstract

Liquid products are produced by contact of a mixture of low rank coal and high pyrite oil shale with CO and H2O at elevated temperatures and pressures.

Description

SPECIFICATION Process for obtaining liquid products from solid carbonaceous materials The present invention relates to the production of liquid products from solid carbonaceous materials.

It is known that low rank coals e.g. lignite may be converted to liquid products by bringing them into contact with CO and H2O at elevated temperatures and pressures. Such a process is disclosed by Sondreal et al, Fuel 1982, 61, October, pp925-938, who also state that the addition of iron pyrite improves product yield and quantity. The reaction in the presence of pyrite was however carried at 425"C.

It is disclosed in US 3617471 that oil shale may be treated with syngas (H2, CO) and H2O at elevated temperatures and pressures, 850"-1000"F (454"C-538"C), 300-1000 psig (2 MPa-6.9 MPa). The specification states, that spent shale can act as a shift catalyst and that the CO fed with the H20 in the treatment of the oil shale undergoes a water gas shift to produce addition of H2 and CO2.

In order to improve the economics of the production of liquid products from low rank coals and oil shales it is desirable to increase the conversion to a levei above that which is at present obtained.

We have now found that by using a specific combination of different types of solid carbonaceous solids higher yields of liquids can be obtained on treatment with CO and H20 than would be predicted from the results of either material treated separately. These high yields can be obtained under relatively mild conditions.

According to the present invention the production of liquid products from solid carbonaceous material by bringing the solid carbonaceous material into contact with CO and H2O at elevated temperature and pressure is characterised in that the solid carbonaceous material is a mixture of low rank coal and high pyrite oil shale.

By "low rank coal" we mean any coal, including peat, having volatile matter greater than 31.1% weight (dry mineral matter free basis), and calorific value (moist mineral matter free basis) less than 11,500 BTU/lb (26.749 MJ/kg), both measured as defined in the ASTM classification of coals.

Examples of low rank coals which may be used in the process of the present invention are Victorian Brown coals.

The oil shale used in the process of the present invention is a high pyrite shale. By "high pyrite oil shale" we mean an oil shale containing preferably at least 0.5% pyritic sulphur (dry basis), and more preferably at least 2% pyritic sulphur (dry basis).

The CO may be fed to the reaction in the form of a CO-rich syngas for example having a CO:H2 molar ratio preferably of at least 0.25:1, more preferably of at least 1:1. The CO may be fed substantially free of H2.

H2O must be present in the reaction. However, many low rank coals contain considerable amounts of moisture and when using such coals it is not always necessary to add H2O to the reaction. Examples of H2O contents in the reaction mixture which may be used are 20% to 80% wt The relative weight ratio of low rank coal and oil shale may for example be in the range 1:1 to 20:1.

The temperature is preferably within the range 250-500", more preferably 300-400"C, most preferably 325 to 4000C.

The pressure may for example be in the range 50 to 300 bar (5 to 30 MPa).

Apparatus suitable for carrying out reactions of this type will be well known to those skilled in the art. The process is conveniently carried out by comminuting the low rank coal and oil shale and optionally suspending the solids in a liquid medium. The liquid medium may for example be water our a phenol e.g.

cresol.

The invention will now be illustrated by reference to the following experiments.

The coal, oil shale and solvent were thoroughly mixed and poured into an autoclave, which was then charged with gas to the required pressure.

The autoclave used was of nominal 30 cm3 volume and designed so that rapid heat up could be achieved by immersion in a fluidised bed sand bath set to the required temperature, whilst continually being agitated.

Similarly rapid cooling was accomplished by removal from the sand bath, and immersion in a tank of cold water. After quenching the autoclave was degassed, and the contents washed and with 300 ml tetrahydrofuran (THF). These were suspended in an ultrasonic bath for 5 minutes to aid dissolution in the THF, and then passed through a 3 Fm pore size filter to remove any THF insoluble material (defined as residue, which included any unreacted organic material, and all mineral matter). This residue was washed with two further 300 ml aliquots of THF to remove any adhering soluble material. All THF washings were pooled, and the THF removed (rotary evaporator) at a temperature below 50"C under reduced pressure (ca.

0.25 bar) (0.025 MPa).

This product (containing solvent and depolymerised organic material) was added to a 40-fold wt. excess of pentane, and the insoluble material removed by filtration. This fraction was termed asphaltenes + preasphaltenes. The material soluble in pentane (but excluding the original solvent) was termed "oils", and these could be characterised by suitable analytical techniques. The sum of the asphaltenes and preasphaltenes, oils, and coal/oil shale derived gases and water was termed "total conversion".

Comparative Test A This is a comparative test not according to the invention. The carbonaceous solid used was Victorian Brown coal. 8g of coal was used in the state (moist) in which it was received on a dry basis the weight was 3.849 and on a daf basis it was 3.809 (daf = dry ash free).

The reducing gas fed to the apparatus was a CO rich syngas of CO: H2 molar ratio 2:1 at a pressure of 70 bar at 25"C. The liquid medium used to suspend the Victorian Brown coal was m-cresol. The reaction was carried out at 3250C for 60 minutes. On completion of the reaction the content of (a) asphaltenes and pre-asphaltenes, and (b) oils, gas and water were determined and the total conversion calculated. The results are given in Table 1.

Comparative Test B This is a comparative example not according to the invention.

The carbonaceous solid was Kentucky Oil shale. 4.019 in the state in which it was received (ground to less than 500 micrometres) was fed to the reactor. The content of iron pyrite was approximately 7% wt. The weight on a dry basis was 3.959 and analysis showed that the content of organic material was 0.609. The reaction conditions were as in Comparative Test A. The results are shown in Table 1.

Example 1 An experiment was carried out as in Comparative Test A but using a mixture of Victorian Brown coal and Kentucky Oil shale in the quantities used in the Tests A and B. The results are shown in Table 1 together with the results which would be predicted from the results obtained in Tests A and B.

Comparative Test C An experiment was carried out as in Comparative Test A but using water in place of m-cresol as the liquid medium. The quantity of Victorian Brown coal used was 6.00g. The coal was used in the state in which it was received. On a dry basis the weight was 2.89g and on a daf basis it was 2.86g The results are shown in Table 2.

Comparative Test D An experiment was carried out as in Comparative Test B but using water in place of m-cresol and using 6.009 of Kentucky Oil shale. On a dry basis the weight was 5.919. The content of organic materials was 0.90.

The results are shown in Table 2.

Example 2 An experiment was carried out as in Comparative Test C and D but using a mixture of Victorian Brown coal and Kentucky Oil shale in the quantities used in Test C and D. The results obtained are shown in Table 2.

Comparative Test E An experiment was carried out using the apparatus used in Comparative Test A. No added liquid medium was used. The gas fed was CO with a pressure at 25"C of 35 bar (3.5 MPa). 5.00g of Victorian Brown coal was used in the state in which it was received. The weight on the dry basis was 1.999 and on a daf basis was 1.979. The reaction was carried at 400"C for 30 minutes. The results are given in Table 3.

Comparative Test F An experiment was carried out as in Comparative Test E but using 5.009 of Kentucky Oil shale. The weight in a dry basis was 4.939 and the content of organic material was 0.759. The results are shown in Table 3.

Example 3 An experiment was carried out as in Comparative Tests E and F but using a mixture of Victorian Brown coal and Kentucky Oil shale in the quantities used in the two earlier tests. The results obtained are shown in Table 3 together with the results which would have been predicted from the results of Comparative Tests E and F.

The experiments show a very considerable increase in total conversion when using a mixture of the coal and shale.

TABLE 1 Total Conversion Experiment A+P O+G+W % (g) (g) (dry mineral matter free basis A 1.62 0.90 66 B 0.02 0.4 27 1 (predicted) 1.64 1.04 61 1 (observed) 2.53 0.72 74 TABLE 2 Experiment A + P O G Total Conversion (9) (9) (9) % (dry mineral matter free basis) C 0.63 0.17 0.29 38 D 0.06 0.06 0.05 19 2 (predicted) 0.69 0.23 0.34 34 2 (observed) 1.42 0.21 0.36 53 A + P = asphaltenes + preasphaltenes O = oil G = gas W = water TABLE 3 Experiment A + P O G Total Conversion (9) (9) (9) % (dry mineral matter free basis) E 0.08 0.19 0.22 25% F 0.24 0.22 0.12 77% 3 (predicted) 0.32 0.41 0.34 39% 3 (observed) 0.57 0.47 0.37 52%

Claims (5)

1. The process for the production of liquid products from solid carbonaceous material which comprises bringing the solid carbonaceous material into contact with CO and H2O at elevated temperatures and pressure is characterised in that the solid carbonaceous material is a mixture of low rank coal and high pyrite oil shale and the temperature is in the range 250"C to 500"C.

2. The process according to claim 1 wherein the coal is Victorian Brown coal.

3. The process according to either of claims 1 or 2 wherein the oil shale contains at least 2% by weight of pyrite sulphur (calculated on a dry basis)

4. The process according to any one of the preceding claims wherein the temperature is in the range 300 to 400 C

5. The process according to any one of the preceding claims wherein the pressure is in the range 5 to 30 MPa.