CN118270847A - Preparation method of novel oxygen carrier for preparing synthesis gas by chemical looping gasification - Google Patents
Preparation method of novel oxygen carrier for preparing synthesis gas by chemical looping gasification Download PDFInfo
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- 229910052760 oxygen Inorganic materials 0.000 title claims abstract description 109
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 title claims abstract description 107
- 239000001301 oxygen Substances 0.000 title claims abstract description 107
- 239000007789 gas Substances 0.000 title claims abstract description 57
- 230000015572 biosynthetic process Effects 0.000 title claims abstract description 45
- 238000003786 synthesis reaction Methods 0.000 title claims abstract description 45
- 239000000126 substance Substances 0.000 title claims abstract description 38
- 238000002309 gasification Methods 0.000 title claims abstract description 37
- 238000002360 preparation method Methods 0.000 title claims abstract description 14
- 239000003245 coal Substances 0.000 claims abstract description 28
- 229910052799 carbon Inorganic materials 0.000 claims abstract description 26
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims abstract description 25
- 238000000034 method Methods 0.000 claims abstract description 17
- 238000002156 mixing Methods 0.000 claims abstract description 4
- 238000011049 filling Methods 0.000 claims abstract description 3
- KRKNYBCHXYNGOX-UHFFFAOYSA-N citric acid Chemical compound OC(=O)CC(O)(C(O)=O)CC(O)=O KRKNYBCHXYNGOX-UHFFFAOYSA-N 0.000 claims description 33
- 238000010438 heat treatment Methods 0.000 claims description 20
- 238000011068 loading method Methods 0.000 claims description 18
- 239000000203 mixture Substances 0.000 claims description 14
- 238000003756 stirring Methods 0.000 claims description 13
- VHUUQVKOLVNVRT-UHFFFAOYSA-N Ammonium hydroxide Chemical compound [NH4+].[OH-] VHUUQVKOLVNVRT-UHFFFAOYSA-N 0.000 claims description 9
- 235000011114 ammonium hydroxide Nutrition 0.000 claims description 9
- 230000008569 process Effects 0.000 claims description 9
- 238000002474 experimental method Methods 0.000 claims description 8
- 239000012298 atmosphere Substances 0.000 claims description 4
- 150000001768 cations Chemical class 0.000 claims description 4
- 239000000499 gel Substances 0.000 claims description 4
- 239000003077 lignite Substances 0.000 claims description 4
- 239000011259 mixed solution Substances 0.000 claims description 4
- 239000011240 wet gel Substances 0.000 claims description 4
- 238000001354 calcination Methods 0.000 claims description 3
- 238000001816 cooling Methods 0.000 claims description 2
- 238000001035 drying Methods 0.000 claims description 2
- 238000000227 grinding Methods 0.000 claims description 2
- 230000001105 regulatory effect Effects 0.000 claims description 2
- 238000001291 vacuum drying Methods 0.000 claims description 2
- 238000007873 sieving Methods 0.000 claims 1
- 238000006243 chemical reaction Methods 0.000 abstract description 26
- 238000003980 solgel method Methods 0.000 abstract description 3
- 239000000446 fuel Substances 0.000 abstract description 2
- XLOMVQKBTHCTTD-UHFFFAOYSA-N Zinc monoxide Chemical compound [Zn]=O XLOMVQKBTHCTTD-UHFFFAOYSA-N 0.000 description 48
- 239000011787 zinc oxide Substances 0.000 description 24
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 8
- OBOXTJCIIVUZEN-UHFFFAOYSA-N [C].[O] Chemical compound [C].[O] OBOXTJCIIVUZEN-UHFFFAOYSA-N 0.000 description 8
- 229910002554 Fe(NO3)3·9H2O Inorganic materials 0.000 description 7
- IWOUKMZUPDVPGQ-UHFFFAOYSA-N barium nitrate Inorganic materials [Ba+2].[O-][N+]([O-])=O.[O-][N+]([O-])=O IWOUKMZUPDVPGQ-UHFFFAOYSA-N 0.000 description 7
- 239000008367 deionised water Substances 0.000 description 7
- 229910021641 deionized water Inorganic materials 0.000 description 7
- 230000000694 effects Effects 0.000 description 7
- 239000002184 metal Substances 0.000 description 7
- 229910052751 metal Inorganic materials 0.000 description 7
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Chemical compound O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 7
- 239000012299 nitrogen atmosphere Substances 0.000 description 6
- 230000008021 deposition Effects 0.000 description 3
- 229910052742 iron Inorganic materials 0.000 description 3
- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 description 2
- HCHKCACWOHOZIP-UHFFFAOYSA-N Zinc Chemical compound [Zn] HCHKCACWOHOZIP-UHFFFAOYSA-N 0.000 description 2
- 238000004458 analytical method Methods 0.000 description 2
- 239000000969 carrier Substances 0.000 description 2
- 230000000052 comparative effect Effects 0.000 description 2
- 230000007547 defect Effects 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 238000000921 elemental analysis Methods 0.000 description 2
- 239000000463 material Substances 0.000 description 2
- 238000011160 research Methods 0.000 description 2
- 238000005245 sintering Methods 0.000 description 2
- 229910052725 zinc Inorganic materials 0.000 description 2
- 239000011701 zinc Substances 0.000 description 2
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 1
- MYMOFIZGZYHOMD-UHFFFAOYSA-N Dioxygen Chemical compound O=O MYMOFIZGZYHOMD-UHFFFAOYSA-N 0.000 description 1
- -1 H 2 Chemical class 0.000 description 1
- 229910001030 Iron–nickel alloy Inorganic materials 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 239000011280 coal tar Substances 0.000 description 1
- 229910017052 cobalt Inorganic materials 0.000 description 1
- 239000010941 cobalt Substances 0.000 description 1
- GUTLYIVDDKVIGB-UHFFFAOYSA-N cobalt atom Chemical compound [Co] GUTLYIVDDKVIGB-UHFFFAOYSA-N 0.000 description 1
- 239000002131 composite material Substances 0.000 description 1
- 229910052802 copper Inorganic materials 0.000 description 1
- 239000010949 copper Substances 0.000 description 1
- 238000010168 coupling process Methods 0.000 description 1
- 230000003670 easy-to-clean Effects 0.000 description 1
- 238000005265 energy consumption Methods 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 238000003912 environmental pollution Methods 0.000 description 1
- 230000002349 favourable effect Effects 0.000 description 1
- 238000002844 melting Methods 0.000 description 1
- 230000008018 melting Effects 0.000 description 1
- 229910044991 metal oxide Inorganic materials 0.000 description 1
- 150000004706 metal oxides Chemical class 0.000 description 1
- 150000002739 metals Chemical class 0.000 description 1
- 238000001000 micrograph Methods 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 229910052759 nickel Inorganic materials 0.000 description 1
- 150000002926 oxygen Chemical class 0.000 description 1
- 238000006116 polymerization reaction Methods 0.000 description 1
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Abstract
The invention belongs to the technical field of energy and chemical industry, and discloses a preparation method of a novel oxygen carrier for preparing synthesis gas by chemical chain gasification, which comprises the following steps: firstly preparing ZnO-BaFe 2O4 oxygen carrier by sol-gel method, then mixing and filling the coal semicoke and BaFe 2O4 oxygen carrier into a fixed bed reactor, and carrying out chemical chain gasification to prepare synthesis gas. The invention solves the problems that the carbon conversion rate is not high when the Fe-based oxygen carrier is used for chemical chain gasification, so that the selectivity of the synthesis gas is not high, and the selectivity of the synthesis gas to CO is not high in particular. Meanwhile, the ZnO is adopted to modify the BaFe 2O4 oxygen carrier, so that the gasification performance is improved, and the application value is higher. The CO-rich synthetic gas prepared by the method has wide application prospect in deep processing of fuel or chemicals.
Description
Technical Field
The invention belongs to the technical field of energy and chemical industry, and particularly relates to a preparation method of a novel oxygen carrier in a chemical chain gasification process.
Background
Coal is a fossil energy source and an important raw material that is difficult to clean and utilize relative to oil and gas. The coal gasification process is essentially a process that converts solids, which are difficult to process and remove, of unwanted components into a gas that is easy to clean and easy to use, and in short, C, H in the coal into clean syngas. Coal gasification is an important way for efficient clean utilization of coal. The chemical chain gasification technology is one of clean and efficient coal resource utilization modes, and has great significance in solving the problems of energy supply, environmental pollution and the like in China. The oxygen is transferred to the coal semicoke through an intermediate medium of an oxygen carrier, so that small molecules such as H 2、CH4、CO、CO2 and the like which can be trapped are decomposed. The oxygen carrier emits heat in the oxygen release process, can provide heat for the subsequent process flow, and can also play a role of a heat carrier. The reduced oxygen carrier can remove carbon deposition through air calcination, and can realize the regeneration of the oxygen carrier. As a research result of the subject group, CN107325846a discloses a coal pyrolysis chemical chain gasification coupling process based on low-rank coal cascade utilization, which is mainly a set of system for completing chemical chain gasification reaction by using an oxygen carrier and simultaneously performing heat transfer as a heat carrier so as to realize circulation. Compared with the traditional gasification system, the chemical chain gasification is favorable for CO 2 collection and treatment, does not need to additionally add excessive CO 2 separation devices, saves cost and also protects the environment. And secondly, the adopted oxygen carrier omits the preparation process of pure oxygen, saves the cost and improves the utilization efficiency of energy sources.
In the prior art, the iron-based oxygen carrier has low price and wide sources, and is not easy to generate carbon deposition, but the iron-based oxygen carrier has weak reducibility, poor selectivity and low conversion rate of fuel, and the iron-based oxygen carrier has good reactivity and poor oxygen carrying capacity only at a higher temperature. The copper-based oxygen carrier has low melting point, is not high-temperature resistant and is easy to agglomerate. The nickel-based oxygen carrier has strong oxygen carrying capacity, higher reaction activity and high temperature resistance, but has insufficient strength, and carbon deposition is easy to occur. The cobalt-based oxygen carrier has high reaction activity and strong oxygen carrying capacity, but is expensive and can pollute the environment. The single metal oxygen carrier has the defects, and a composite metal oxygen carrier prepared by two or more metals is used as a research hot spot, for example, the CuFe 2O4 oxygen carrier can be subjected to chemical chain gasification at a lower temperature, but oxygen decoupling can occur at about 400 ℃, so that the preparation of CO is not facilitated, and meanwhile, serious sintering is carried out; the NiFe 2O4 oxygen carrier has relatively low activity when undergoing chemical chain gasification, and cannot fully react materials, so that high synthesis gas selectivity and high carbon conversion rate cannot be obtained.
Based on the problems in the single metal oxygen carrier and two or more metal oxygen carriers described above, it is necessary to develop an oxygen carrier with better performance.
Disclosure of Invention
The invention provides a preparation method of a novel oxygen carrier for preparing synthesis gas by chemical looping gasification, which overcomes the defects of the prior art. The BaFe 2O4 oxygen carrier prepared by the sol-gel method has the characteristics of high synthesis gas selectivity, good CO selectivity, high temperature resistance, sintering resistance and the like, the performance of the oxygen carrier can be further improved by modifying the BaFe 2O4 oxygen carrier by zinc metal, so that the high synthesis gas selectivity, high carbon conversion rate and high CO selectivity are maintained in the chemical chain gasification process, and meanwhile, the service life of the BaFe 2O4 oxygen carrier can be prolonged by modifying the BaFe 2O4 oxygen carrier by zinc metal, the oxygen carrying and oxygen releasing performances of the oxygen carrier are improved, and the optimal temperature required by chemical chain gasification is reduced.
The technical scheme of the invention is as follows:
the preparation method of the novel oxygen carrier for preparing the synthesis gas by chemical looping gasification comprises the following steps:
Preparation of ZnO-BaFe 2O4 oxygen carrier with different proportions by sol-gel method
Firstly, preparing Fe (mixed solution of NO 3)3·9H2 O and Ba (NO 3)2), wherein the molar ratio of Ba to Fe is 1:2, the total cation concentration is 1mol/L, adding citric acid into the mixed solution according to the molar ratio of citric acid to cations is 1.5:1, fully stirring at room temperature until the mixture is uniform, adding ZnO, regulating pH=7 by ammonia water, continuously stirring until the mixture is completely dissolved, continuously stirring at 90 ℃ for 5-6h to form wet gel, placing the wet gel in a constant temperature vacuum drying oven for drying at 120 ℃ for 10h to obtain dry gel, pre-calcining the dry gel at 200 ℃ for 10-20min, setting a heating program to be 5 ℃/min to 500 ℃ for 1h at constant temperature, continuously heating to 900 ℃ for 5h at constant temperature at 5 ℃/min, naturally cooling to room temperature, and grinding and screening to obtain ZnO-BaFe 2O4 oxygen carrier, wherein the ZnO loading amount is 5% -25%.
A method for preparing synthesis gas by using novel oxygen carrier to realize fixed bed chemical chain gasification comprises the following steps:
Uniformly mixing coal semicoke and ZnO-BaFe 2O4 oxygen carrier, filling the mixture into a reactor, and carrying out a fixed bed experiment to prepare the synthesis gas, wherein the fixed bed experiment is to heat the reactor to 900 ℃ at a heating rate of 40 ℃/min under the atmosphere of N 2 and keep the temperature for 60 minutes to obtain a gas product rich in the synthesis gas.
The coal semicoke is semicoke obtained by pyrolyzing Bai Yinhua lignite in a tube furnace at 500 ℃ for 1 hour, and crushing the semicoke to below 80 meshes, wherein the oxygen-carbon ratio of the coal semicoke to the ZnO-BaFe 2O4 oxygen carrier in the experiment is 1:1.
The invention has the beneficial effects that:
(1) The ZnO-BaFe 2O4 oxygen carrier can be used for improving the ratio of the synthetic gas in the gasified gas product, compared with an unmodified parent BaFe 2O4 oxygen carrier, the relative content of the synthetic gas is improved, wherein the CO yield is up to 1.04m < 3 >/kg, and the relative content of the synthetic gas is increased by 28.4% compared with the parent BaFe 2O4 oxygen carrier; the highest yield of H 2 reaches 0.28m3/kg, the oxygen carrier is increased by 27.3% compared with that of the parent BaFe 2O4, the carbon conversion rate reaches 94.56%, the oxygen carrier is increased by 15.43% compared with that of the parent BaFe 2O4, and the modified oxygen carrier has high synthesis gas selectivity and CO selectivity while ensuring high conversion rate.
(2) According to the experimental method, an active metal oxide ZnO is adopted to modify the BaFe 2O4 oxygen carrier, and the reduction peak of the modified BaFe 2O4 oxygen carrier is advanced as shown in the H 2 -TPR chart, so that the oxygen carrier can release oxygen at a lower temperature, the oxygen release performance of the oxygen carrier is greatly improved, the energy consumption is reduced, and the reaction activity of the oxygen carrier is improved. In addition, from the SEM spectrogram, the polymerization degree of the ZnO-supported BaFe 2O4 oxygen carrier is higher. In addition, the zinc oxide source is wide, and the method is used for preparing the synthetic gas by chemical chain gasification, so that the efficient clean utilization of coal is realized, and the method has profound significance for producing basic chemical products.
Drawings
FIG. 1 is a diagram of a BaFe 2O4 oxygen carrier scanning electron microscope;
FIG. 2 is a scanning electron microscope image of a 20% ZnO loaded BaFe 2O4 oxygen carrier;
FIG. 3 is a graph of the BaFe 2O4 oxygen carrier and 20% ZnO loaded BaFe 2O4 oxygen carrier H 2 -TPR;
FIG. 4 is an XRD spectrum of a BaFe 2O4 oxygen carrier with different ZnO loadings; (wherein the loading of ZnO is 5%, 10%, 15%, 20%, 25%);
FIG. 5 is a schematic diagram showing the effect of different ZnO loaded BaFe 2O4 oxygen carriers on different gas contents;
FIG. 6 is a graph showing the effect of BaFe 2O4 oxygen carrier on char chemical chain gasification cycle performance at 900 ℃.
FIG. 7 is a graph showing the effect of 20% ZnO loaded BaFe 2O4 oxygen carrier char chemical chain gasification cycle performance at 900 ℃;
FIG. 8 is a flow chart of the preparation of BaFe 2O4 oxygen carrier;
FIG. 9 is a flow chart of the preparation of the modified BaFe 2O4 oxygen carrier.
Detailed Description
The following describes the embodiments of the present invention further with reference to the drawings and technical schemes.
The percentage designed in the following examples is mass percent (%) by adopting the novel oxygen carrier for preparing the synthetic gas by chemical looping gasification, and industrial analysis and elemental analysis of Bai Yinhua lignite and semicoke thereof in the experiment are shown in table 1.
Table 1 Bai Yinhua Industrial analysis and elemental analysis of Brown coal and its semicoke
Note that: * Obtained by subtraction
Example 1
Firstly, using a parent BaFe 2O4 oxygen carrier, mixing coal semicoke and the parent BaFe 2O4 oxygen carrier according to the ratio of oxygen to carbon of 1:1, and then loading the mixture into a fixed bed reactor for chemical chain gasification.
Secondly, heating the fixed bed reactor to 900 ℃ at a heating rate of 40 ℃/min under an N 2 atmosphere and maintaining for 60 minutes to prepare synthesis gas, wherein the carbon conversion rate is 79.13% and the selectivity of the synthesis gas is 82.57%; the selectivity to CO was 80.18%; the yield of CO was 0.81m3/kg; the yield of H 2 was 0.23m3/kg; the yield of CH 4 was 0.02m3/kg; the yield of CO 2 was 0.20m3/kg.
Example 2
Firstly, 40.4g of Fe (NO 3)3·9H2O、13.06g Ba(NO3)2, 0.7825g of ZnO and citric acid are mixed and then 150ml of deionized water is added, and ammonia water is added to adjust PH=7 after uniform stirring, wherein the loading capacity of ZnO is 5%;
secondly, the coal semicoke and 5% ZnO-BaFe 2O4 oxygen carrier are mixed according to the oxygen-carbon ratio of 1:1, and then loading the mixture into a fixed bed reactor for chemical chain gasification.
Thirdly, heating the fixed bed reactor to 900 ℃ at a heating rate of 40 ℃/min under an N 2 atmosphere and keeping the temperature for 60 minutes to prepare synthesis gas, wherein the carbon conversion rate is 88.44%; the selectivity of the synthesis gas is 79.97%; the selectivity of CO is 76.82%; the yield of CO was 0.89m3/kg; the yield of H 2 was 0.22m3/kg; the yield of CH 4 was 0.01m3/kg; the yield of CO 2 was 0.27m3/kg. Compared with a parent BaFe 2O4 oxygen carrier, the carbon conversion rate is improved by 9.31 percent; the selectivity of the synthesis gas and the selectivity of CO are slightly reduced; the CO yield is increased by 0.08m3/kg compared with the parent BaFe 2O4 oxygen carrier.
Example 3
Firstly, 40.4g of Fe (NO 3)3·9H2O、13.06g Ba(NO3)2, 1.5650g of ZnO and citric acid are mixed, 150ml of deionized water is added, ammonia water is added after uniform stirring to adjust PH=7, and the loading capacity of ZnO is 10%;
Secondly, the coal semicoke and 10% ZnO-BaFe 2O4 oxygen carrier are mixed according to the oxygen-carbon ratio of 1:1, and then loading the mixture into a fixed bed reactor for chemical chain gasification.
Thirdly, heating the fixed bed reactor to 900 ℃ at a heating rate of 40 ℃/min under an N 2 atmosphere and keeping the temperature for 60 minutes to prepare synthesis gas, wherein the carbon conversion rate is 90.76%; the selectivity of the synthesis gas is 86.58%; the selectivity of CO is 83.36%; the yield of CO was 1.00m3/kg; the yield of H 2 is 0.35m3/kg; the yield of CH 4 was 0.01m3/kg; the yield of CO 2 was 0.20m3/kg. Carbon conversion 11.63% compared to the parent BaFe 2O4 oxygen carrier; the selectivity of the synthesis gas is improved by 4.01 percent; CO selectivity is improved by 3.18%; the CO yield and the H 2 yield are respectively increased by 0.19m3/kg and 0.12m3/kg compared with the parent BaFe 2O4 oxygen carrier.
Example 4
Firstly, 40.4g of Fe (NO 3)3·9H2O、13.06g Ba(NO3)2, 2.3475g of ZnO and citric acid are mixed, 150ml of deionized water is added, ammonia water is added after uniform stirring to adjust PH=7, and the loading capacity of ZnO is 15%;
Secondly, the coal semicoke and 15 percent of ZnO-BaFe 2O4 oxygen carrier are mixed according to the oxygen-carbon ratio of 1:1, and then loading the mixture into a fixed bed reactor for chemical chain gasification.
Thirdly, heating the fixed bed reactor to 900 ℃ at a heating rate of 40 ℃/min under an N 2 atmosphere and keeping the temperature for 60 minutes to prepare synthesis gas, wherein the carbon conversion rate is 91.58%; the selectivity of the synthesis gas is 84.89%; the selectivity of CO is 82.51%; the yield of CO was 0.94m3/kg; the yield of H 2 was 0.23m3/kg; the yield of CH 4 was 0.01m3/kg; the yield of CO 2 was 0.20m3/kg. Compared with a parent BaFe 2O4 oxygen carrier, the carbon conversion rate is improved by 7.45 percent; the selectivity of the synthesis gas is improved by 2.32%; CO selectivity is improved by 2.33%; the CO yield is increased by 0.13m3/kg compared with the parent BaFe 2O4 oxygen carrier.
Example 5
Firstly, 40.4g of Fe (NO 3)3·9H2O、13.06g Ba(NO3)2, 3.13g of ZnO and citric acid are mixed and then 150ml of deionized water is added, and ammonia water is added to adjust PH=7 after uniform stirring, wherein the loading capacity of ZnO is 20%;
Secondly, the coal semicoke and 20 percent of ZnO-BaFe 2O4 oxygen carrier are mixed according to the oxygen-carbon ratio of 1:1, and then loading the mixture into a fixed bed reactor for chemical chain gasification.
Thirdly, heating the fixed bed reactor to 900 ℃ at a heating rate of 40 ℃/min under an N 2 atmosphere and keeping the temperature for 60 minutes to prepare synthesis gas, wherein the carbon conversion rate is 94.56%; the selectivity of the synthesis gas is 85.86%; the selectivity to CO was 84.22%; the yield of CO was 1.04m3/kg; the yield of H 2 was 0.28m3/kg; the yield of CH 4 was 0.02m3/kg; the yield of CO 2 was 0.19m3/kg. Compared with a parent BaFe 2O4 oxygen carrier, the carbon conversion rate is improved by 15.43%; the selectivity of the synthesis gas is improved by 3.29%; the selectivity of CO is improved by 4.04%; the CO yield and the H 2 yield are respectively increased by 0.23m3/kg and 0.05m3/kg compared with the parent BaFe 2O4 oxygen carrier.
Example 6
Firstly, 40.4g of Fe (NO 3)3·9H2O、13.06g Ba(NO3)2, 3.9125g of ZnO and citric acid are mixed, 150ml of deionized water is added, ammonia water is added after uniform stirring to adjust PH=7, and the loading capacity of ZnO is 25%;
Secondly, the coal semicoke and 25% ZnO-BaFe 2O4 oxygen carrier are mixed according to the oxygen-carbon ratio of 1:1, and then loading the mixture into a fixed bed reactor for chemical chain gasification.
Thirdly, heating the fixed bed reactor to 900 ℃ at a heating rate of 40 ℃/min under an N 2 atmosphere and keeping the temperature for 60 minutes to prepare synthesis gas, wherein the carbon conversion rate is 86.76%; the selectivity of the synthesis gas was 88.73%; the selectivity of CO is 86.69%; the yield of CO was 0.99m3/kg; the yield of H 2 was 0.28m3/kg; the yield of CH 4 was 0.01m3/kg; the yield of CO 2 was 0.15m3/kg. Compared with a parent BaFe 2O4 oxygen carrier, the carbon conversion rate is improved by 7.63%; the selectivity of the synthesis gas is improved by 6.16%; CO selectivity is improved by 6.51%; the CO yield and the H2 yield are respectively increased by 0.18m3/kg and 0.05m3/kg compared with the parent BaFe 2O4 oxygen carrier.
Comparative example 1
In the first step, 40.4g of Fe (NO 3)3·9H2O、13.06g Ba(NO3)2 and a certain amount of citric acid) are mixed, 150ml of deionized water is added, and ammonia water is added to adjust the PH to be 7 after uniform stirring, so that a parent BaFe 2O4 oxygen carrier is obtained.
Secondly, the coal semicoke and a parent BaFe 2O4 oxygen carrier are mixed according to an oxygen-carbon ratio of 1:1, and then loading the mixture into a fixed bed reactor for chemical chain gasification.
Thirdly, heating the fixed bed reactor to 900 ℃ at a heating rate of 40 ℃/min under the atmosphere of N 2 and keeping for 60 minutes to prepare the synthesis gas.
Fourth, the reacted oxygen carrier is put into a muffle furnace to be calcined for 60 minutes by air, and the second step and the third step are repeated, so that the selectivity of the synthesis gas is 71.88% after the cycle is carried out for 5 times; the selectivity to CO was 67.25%; the yield of CO was 0.68m3/kg; the yield of H 2 was 0.22m3/kg; the yield of CH 4 was 0.02m3/kg; the yield of CO 2 was 0.33m3/kg.
Comparative example 2
Firstly, 40.4g of Fe (NO 3)3·9H2O、13.06g Ba(NO3)2, 3.9125g of ZnO and a certain amount of citric acid are mixed, 150ml of deionized water is added, ammonia water is added after uniform stirring to adjust PH=7, and the loading amount of ZnO is 20%;
Secondly, the coal semicoke and 20 percent of ZnO-BaFe 2O4 oxygen carrier are mixed according to the oxygen-carbon ratio of 1:1, and then loading the mixture into a fixed bed reactor for chemical chain gasification.
Thirdly, heating the fixed bed reactor to 900 ℃ at a heating rate of 40 ℃/min under the atmosphere of N 2 and keeping for 60 minutes to prepare the synthesis gas.
Fourth, the reacted oxygen carrier is put into a muffle furnace to be calcined for 60 minutes by air, and then the second step and the third step are repeated, so that the carbon conversion rate is 82.64% after the cycle is carried out for 5 times; the selectivity of the synthesis gas is 72.16%; the selectivity to CO was 67.28%; the yield of CO was 0.72m3/kg; the yield of H 2 is 0.26m3/kg; the yield of CH 4 was 0.03m3/kg; the yield of CO 2 was 0.35m3/kg. Compared with the parent BaFe 2O4 oxygen carrier after five times of circulation, the carbon conversion rate is improved by 4.26 percent; the selectivity of the synthesis gas and the selectivity of CO are slightly improved; the CO yield and the H 2 yield are increased by 0.04m3/kg compared with the parent BaFe 2O4 oxygen carrier.
With the increase of the ZnO addition amount, the carbon conversion rate is improved, the synthesis gas selectivity and the CO selectivity are improved, the carbon conversion rate is improved to 94.56% from 79.13%, the synthesis gas selectivity is improved to 88.73% from 82.57%, and the CO selectivity is improved to 86.69%. In addition, the modified BaFe 2O4 oxygen carrier after five cycles has higher carbon conversion rate, synthesis gas selectivity and CO selectivity than the parent BaFe 2O4 oxygen carrier. Therefore, the BaFe 2O4 oxygen carrier with 20% ZnO addition at 900 ℃ is considered to be a proper addition in the coal tar chemical chain gasification experiment. The method is applied to the chemical chain gasification process of the coal semicoke, can realize clean and efficient utilization of coal, can still keep good performance after repeated circulation, greatly improves the selectivity of the synthesis gas, greatly improves the utilization rate of the coal, and has profound significance for producing chemical products with high added values.
While the invention has been described with reference to exemplary embodiments, it should be understood that the invention is not limited to the exemplary embodiments. The scope of the appended claims should also be accorded the broadest interpretation so as to encompass all such modifications and equivalent structures as are well as the equivalent structures and materials that are equivalent to the true spirit of the present invention.
Claims (5)
1. The preparation method of the novel oxygen carrier for preparing the synthesis gas by chemical looping gasification is characterized by comprising the following steps:
Firstly, preparing Fe (mixed solution of NO 3)3·9H2 O and Ba (NO 3)2), wherein the molar ratio of Ba to Fe is 1:2, the total cation concentration is 1mol/L, adding citric acid into the mixed solution according to the molar ratio of citric acid to cations is 1.5:1, fully stirring at room temperature until the mixture is uniform, adding ZnO, regulating pH to 7 by ammonia water, continuously stirring until the mixture is completely dissolved, continuously stirring for 5-6 hours at 90 ℃ to form wet gel, placing the wet gel in a constant temperature vacuum drying oven for drying for 10 hours at 120 ℃ to obtain dry gel, pre-calcining the dry gel at 200 ℃ for 10-20 minutes, setting a heating program to be 5 ℃/min to 500 ℃, keeping the constant temperature for 1 hour, continuously heating to 900 ℃ for 5 hours at 5 ℃/min, naturally cooling to room temperature, and grinding and sieving to obtain the ZnO-BaFe 2O4 oxygen carrier.
2. The method of claim 1, wherein the ZnO-BaFe 2O4 oxygen carrier has a ZnO loading of 5% to 25%.
3. A process for the preparation of synthesis gas by fixed bed chemical looping gasification using a novel oxygen carrier obtained by the preparation process according to claim 1 or 2, characterized by the steps of: uniformly mixing coal semicoke and ZnO-BaFe 2O4 oxygen carrier, filling the mixture into a reactor, and carrying out a fixed bed experiment to prepare the synthesis gas, wherein the fixed bed experiment is to heat the reactor to 900 ℃ at a heating rate of 40 ℃/min under the atmosphere of N 2 and keep the temperature for 60 minutes to obtain a gas product rich in the synthesis gas.
4. The method of claim 3, wherein the ratio of oxygen to carbon of the coal semicoke to the ZnO-BaFe 2O4 oxygen carrier is 1:1.
5. The method according to claim 3 or 4, wherein the coal semicoke is semicoke obtained by pyrolyzing Bai Yinhua lignite in a tube furnace at 500 ℃ for 1 hour, and crushing the semicoke to below 80 meshes.
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