Process for gasification of a carbonaceous raw material of low value as a fuel using a nanocatalyst

Abstract

The present invention describes a mixture comprising carbonaceous raw material of low value as a fuel and a nanocatalyst. The catalytic mixture comprises from 1% to 50% by weight of a nanocatalyst; and from 99% to 50% by weight of carbonaceous raw material selected from petroleum coke, coal, heavy residual fraction of oil, or a mixture thereof. The nanocatalyst comprises a carbon nanomaterial of between 99.99% and 80% by weight in contents and at least one alkali metal of between 0.01% and 20% by weight in contents, based on the total weight of the nanocatalyst, and the specific surface area of the nanocatalyst ranges between 400 and 1300 m2/g. Furthermore, the present invention also describes a process for gasifying the catalytic mixture which comprises the steps of placing the mixture in a gasifier; heating the mixture in the presence of an oxidizing agent selected from air, pure oxygen, carbon dioxide, water vapor, or a mixture thereof at a temperature ranging between 200 and 1,300° C.; and obtaining a gaseous product comprising H2, CO, CO2, CH4.

Claims

1. A catalytic mixture comprising: from 1% to 50% by weight of a nanocatalyst; and from 99% to 50% by weight of carbonaceous raw material of low value as a fuel selected from petroleum coke, coal, residual heavy fraction of petroleum, and a mixture thereof, based on the total weight of the catalytic mixture, wherein the nanocatalyst consists of a carbon nanomaterial in an amount between 99.99% and 80% by weight and at least one alkali metal in an amount between 0.01% and 20% by weight, based on the total weight of the nanocatalyst, and the specific surface area of the nanocatalyst varies between 400 and 1,300 m.sup.2/g.

2. The catalytic mixture according to claim 1, wherein the nanocatalyst consists of the carbon nanomaterial in an amount between 99.99% and 95% by weight and the at least one alkali metal in an amount between 0.01% and 5% by weight, based on the total weight of the nanocatalyst.

3. The catalytic mixture according to claim 1, wherein the specific surface area of the nanocatalyst varies between 500 and 800 m.sup.2/g.

4. The catalytic mixture according to claim 1, wherein the carbon nanomaterial is selected from nanospheres, nanofilaments, nanotubes, and graphenes.

5. The catalytic mixture according to claim 4, wherein the carbon nanomaterial is selected from nanospheres, and nanofilaments.

6. The catalytic mixture according to claim 1, wherein the at least one alkali metal is selected from sodium, potassium, rubidium, and cesium.

7. The catalytic mixture according to claim 6, wherein the at least one alkali metal is potassium.

8. The catalytic mixture according to claim 1, wherein the carbonaceous raw material is petroleum coke, coal, or a mixture thereof.

9. The catalytic mixture according to claim 8, wherein the carbonaceous raw material is petroleum coke.

10. The catalytic mixture according to claim 8, wherein the carbonaceous raw material is coal.

11. The catalytic mixture according to claim 1, wherein the mixture comprises 50% of the nanocatalyst and 50% of the carbonaceous raw material.

12. A gasification process of the catalytic mixture of claim 1, comprising the following steps: introducing the catalytic mixture in a gasifier; heating the catalytic mixture in the presence of an oxidizing agent selected from air, pure oxygen, carbon dioxide, water vapor, and a mixture thereof to a temperature ranging between 200 and 1300° C.; and obtaining a gaseous product comprising H.sub.2, CO, CO.sub.2, and CH.sub.4.

13. The process according to claim 12, wherein the step of heating the catalytic mixture is carried out at a temperature range between 900 and 1,200° C.

14. The process according to claim 12, wherein the oxidizing agent is diluted in an inert gas.

15. The catalytic mixture according to claim 1, wherein the carbonaceous raw material is residual heavy fraction of petroleum.

Description

BRIEF DESCRIPTION OF THE FIGURES

(1) The detailed description below refers to the attached figures, which:

(2) FIG. 1 depicts the graph of conversion (%) of samples comprising petroleum coke in the range of 0 to 50% according to the temperature variation (° C.).

(3) FIG. 2 depicts the graph of conversion (%) of samples comprising petroleum coke at a temperature of 700° C.

(4) FIG. 3 depicts the graph of conversion (%) of samples comprising petroleum coke at a temperature of 800° C.

(5) FIG. 4 depicts the graph of conversion (%) of samples comprising petroleum coke at 900° C.

(6) FIG. 5 depicts the graph of the conversion (%) of samples comprising petroleum coke in the range of 0 to 100% according to the temperature variation (° C.).

DETAILED DESCRIPTION OF THE INVENTION

(7) The present invention refers to a mixture comprising carbonaceous raw material of fossil source of low value as a fuel and a nanocatalyst. The mixture comprises from 1% to 50% by weight of a nanocatalyst and from 99 to 50% by weight of carbonaceous raw material, based on the total weight of the mixture.

(8) The nanocatalyst used in the mixture of the present invention consists of a carbon nanomaterial containing at least one alkali metal.

(9) Carbon nanomaterial is present in a content between 99.99% and 80% by weight, and at least one alkali metal is present in a content between 0.01% and 20% by weight, based on the total weight of the nanocatalyst. Preferably, the carbon nanomaterial is present in the nanocatalyst in a content between 99.99% and 95% by weight and at least one alkali metal in a content between 0.01% and 5% by weight.

(10) The specific surface area of the nanocatalyst in the mixture described herein is greater than 400 m.sup.2/g, ranging between 400 and 1,300 m.sup.2/g. Preferably, the specific surface area of the nanocatalyst is between 500 and 800 m.sup.2/g.

(11) The carbon nanomaterial present in the nanocatalyst of the invention described herein comes from petroleum fractions as carbon sources and can be obtained through usual processes already described in the state of the art. Carbon nanomaterial is selected from nanospheres, nanofilaments, nanotubes or graphenes.

(12) In a preferred embodiment of the present invention, carbon nanospheres or nanofilaments are used in the nanocatalyst, which are obtained from heavy fractions of oil according to the process described in PI 0806065-7, which is incorporated by reference.

(13) The carbon nanomaterial exhibits over the entire specific surface area of the nanocatalyst, regions made up of polycondensed aromatic ring systems. These regions can provide attractive intermolecular interactions of the π-π type having aromatic structures of the carbonaceous raw material dispersed in the reaction medium during the gasification process.

(14) The intermolecular interactions mentioned above allow the optimization of the contact of these aromatic structures with the catalytic sites of alkali metals present on the nanocatalyst surface, which makes it possible to achieve better conversion results for the carbonaceous raw material to be gasified.

(15) Any alkali metal can be used in the nanocatalyst of the present invention. In a preferred embodiment, at least one alkali metal is selected from sodium, potassium, rubidium and cesium. Most preferably, potassium is used.

(16) Thus, the nanocatalyst present in the mixture combines the great specific surface area of carbon nanomaterials with the presence of alkali metal catalytic sites favorable to the gasification reaction.

(17) The carbonaceous raw material present in the catalytic mixture is selected from petroleum coke, coal or mixture thereof. Preferably, petroleum coke is used as a carbonaceous raw material.

(18) The present invention also provides a process for gasifying the catalytic mixture described herein.

(19) The process comprises the following steps: introducing the catalytic mixture in an gasifier; heating the mixture in the presence of an oxidizing agent selected from air, pure oxygen, carbon dioxide, water vapor or a mixture thereof to a temperature ranging between 200 and 1,300° C.: and obtaining a gaseous product comprising H.sub.2, CO, C.sub.2, CH.sub.4.

(20) Preferably, the temperature range used in the heating step of the process ranges between 900 and 1,200° C.

(21) In the context of the present invention, the term “gasifier” refers to any type of gasifier present in the state of the art, such as fixed bed gasifier, fluidized bed gasifier or indirect gasifier.

(22) In a way of implementing the gasification process described herein, the gaseous product obtained further comprises, in lower ratios, hydrocarbon compounds.

(23) In an alternative embodiment, the oxidizing agent may be diluted in an inert gas, such as a noble gas.

(24) The process of present invention, when compared with conventional processes described in the prior art, can achieve greater conversions at the same temperature or further similar conversions at lower temperatures.

(25) Thus, the gasification process disclosed herein allows greater energy gain, in addition to allowing less generation of residues, since the nanocatalyst used has the same chemical nature as the carbonaceous raw material.

(26) The following description will start from preferred embodiments of the invention. As will be apparent to any person skilled in the art, the invention is not limited to these embodiments in particular.

EXAMPLES

(27) Three tests of the gasification process of present invention were carried out using the catalytic mixture described herein. Two comparative tests were also carried out, one using a traditional material (herein called as inert) and the other without a nanocatalyst (only pure petroleum coke).

(28) Test 1—Gasification Process Having Petroleum Coke and 50% Inert

(29) A sample with petroleum coke was mixed in equal parts with a commercial alpha alumina with approximately 2 m.sup.2/g of specific surface area measured by BET, hereinafter referred to as inert.

(30) The sample of 50% inert and 50% coke was heated in a flow of a gas mixture of synthetic air (19.4%), helium (77.6%) and water vapor (3%), the latter being fed by a saturator maintained at 24° C. The temperature range used was from 50 to 1.200° C. at a rate of 10° C./min.

(31) Test 2—Gasification Process Having Nanocatalyst and 50% Coke

(32) The sample tested was a catalytic mixture of petroleum coke and the nanocatalyst of the present invention. The carbon nanomaterial present in the tested nanocatalyst is in the form of nanospheres.

(33) The sample was heated in a flow of a gaseous mixture of synthetic air (19.4%), Helium (77.6%) and water vapor (3%), the latter being fed by a saturator maintained at 24° C. The temperature range used was of 50 to 1,200° C. at a rate of 10° C./min.

(34) Test 3—Gasification Process Having 25% Nanocatalyst and 75% Coke

(35) The sample tested was the catalytic mixture comprising 75% petroleum coke and 25% nanocatalyst. The carbon nanomaterial present in the nanocatalyst tested is in the form of nanospheres.

(36) The sample was heated in a flow of a gaseous mixture of synthetic air (19.4%), Helium (77.6%) and water vapor (3%), the latter being fed by a saturator maintained at 24° C. The temperature range used was of 50 to 1,200° C. at a rate of 10° C./min.

(37) Test 4—Gasification Process Having 12.5% Nanocatalyst and 87.5% Coke

(38) The sample tested was the catalytic mixture comprising 87.5% petroleum coke and 12.5% nanocatalyst. The carbon nanomaterial present in the tested nanocatalyst is in the form of nanospheres.

(39) The sample was heated in a flow of a gaseous mixture of synthetic air (19.4%), Helium (77.6%) and water vapor (3%), the latter being fed by a saturator maintained at 24° C. The temperature range used was de 50 to 1.200° C. at a rate of 10° C./min.

(40) Test 5—Gasification Process Having 100% Pure Coke

(41) The sample tested was pure coke, absent from any catalyst. The sample was heated in a flow of a gas mixture of synthetic air (19.4%), Helium (77.6%) and water vapor (3%), the latter being fed by a saturator maintained at 24° C. The temperature range used was of 50 to 1,200° C. at a rate of 10° C./min.

(42) Comparative Results

(43) First, the value of 50% conversion of the samples was considered, this conversion being measured by the loss of mass in the TGA.

(44) It can be seen in FIG. 1 that the presence of nanocatalysts containing carbon nanospheres in different proportions resulted in greater conversions from 400° C. in test 4, from 380° C. in test 3 and from 200° C. in test 2.

(45) In addition, it can also be seen in FIG. 1 that the value of 50% conversion of the sample was reached at a temperature of 917° C. during test 2, close to 970° C. during tests 3 and 4 and only in the temperature of 1,137° C. in test 1.

(46) It is verified, then, that it was necessary to provide 220° C. more in the temperature of the gasification process using a sample of coke and inert to achieve the same conversion of test 2.

(47) Thus, it is observed that the gasification process of test 2 occurs at a lower temperature, which results in savings in the supply of energy to the process, in addition to lower operating costs.

(48) FIGS. 2, 3 and 4 depict the conversion of the samples, according to tests 1 to 5, at temperatures of 700° C., 800 and 900° C., respectively.

(49) It is noted that the conversion of the samples is greater the higher the process temperature, according to tests 1 to 5. At the temperature of 900° C. (FIG. 4), it is noted that 47% of the test sample 2 were converted and only 33% of the sample of test 1.

(50) It is also noted that test 2 (sample of the catalytic mixture with 50% nanocatalyst and 50% petroleum coke) shows the highest conversion at all temperatures evaluated.

(51) Likewise, it is noted that tests 3 and 4, in which the nanocatalyst is used in smaller proportions, exhibits sample conversion values close to the result obtained in test 2 at the evaluated temperatures.

(52) In FIG. 5, it is noted that the maximum conversion of the sample of test 5 at the temperature of 1.200° C. is only 63%.

(53) At that same temperature, it is noted that the conversion of the sample of test 2 is of 98%, that is, the catalytic mixture with coke and nanocatalyst in the proportion of 50% was almost all converted into a gaseous product comprising H.sub.2, CO, CO.sub.2, CH.sub.4. Thus, the formation of residues in the gasification process is minimized.

(54) It is also noted that the maximum conversion achieved by tests 3 and 4 at 1,200° C. is of 90% and 80%, respectively.

(55) Therefore, it was possible to demonstrate that the gasification process according to the present invention obtains greater conversions at the same temperature or further equal conversions at a lower temperature compared to processes not using the catalytic mixtures described herein.

(56) The description that has been made so far of the object of the present invention should be considered only as a possible embodiment or possible embodiments, and any specific characteristic introduced therein should be understood only as something that has been written to facilitate understanding.

(57) Thus, it is emphasized the fact that several variations involving the scope of protection of this application are allowed, the present invention not being limited to the specific configurations/embodiments described above.