Method for producing hydrogen through calcium oxide cooperating with sodium metaaluminate adsorption-catalysis reinforcement charcoal gasification
By using calcium oxide synergistic sodium metaaluminate and bamboo carbonate in the hydrogen production reactor, the problems of insufficient gasification activity of calcium-based adsorbents and alkali metal carbonate catalysts in the prior art during hydrogen production process are solved, and high hydrogen yield and high concentration of hydrogen are achieved, and the catalyst is stable, achieving net negative emissions.
Patent Information
- Application Number
- CN202411950969.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-12-27
- Publication Date
- 2025-04-08
AI Technical Summary
In the prior art, calcium-based adsorbents and alkali metal carbonate catalysts have problems such as insufficient gasification activity during hydrogen production, low hydrogen yield, and easy deactivation of the catalyst at high temperatures.
Calcium oxide synergistic sodium metaaluminate is used as the adsorption-catalyst. By combining it with bamboo charcoal in the hydrogen production reactor, 60% water vapor/nitrogen is introduced to react at a certain temperature, achieving high yield and high concentration of hydrogen.
The hydrogen yield and concentration are improved, the catalyst is maintained with high activity, and the high concentration of CO2 is generated, achieving net negative emissions.
Smart Images
Figure CN119776032A_ABST
Abstract
Description
Technical Field
[0001] The invention relates to the technical field of adsorption-catalysis enhanced gasification hydrogen production, and in particular to a method for adsorption-catalysis enhanced gasification hydrogen production with calcium oxide in coordination with sodium aluminate. Background Art
[0002] As an ideal clean energy, hydrogen has the advantages of high combustion calorific value and no pollution, and its preparation method has attracted much attention. Biomass gasification hydrogen production technology has the advantages of wide raw material sources, low cost and abundant raw material sources. However, there are problems such as insufficient gasification activity, complex synthesis gas composition, low H2 conversion rate and concentration in the hydrogen production process, which limit its application scope.
[0003] Currently, researchers use calcium-based materials to absorb carbon dioxide to enhance biomass gasification and hydrogen production, but the gasification effect is not ideal and the hydrogen output is low. Some researchers also add additional catalysts to further improve the gasification activity. The most commonly used catalyst is alkali metal carbonate, but it is easy to react with ash at high temperatures and become deactivated, resulting in catalyst loss, which is not conducive to recovery. Therefore, it is particularly important to select a suitable alternative catalyst.
[0004] In order to solve the problems of insufficient gasification activity of calcium-based adsorbents and alkali metal carbonate catalysts in hydrogen production, low hydrogen production, and easy deactivation of catalysts at high temperatures, the present invention provides a method for enhancing gasification hydrogen production by adsorption-catalysis of calcium oxide in coordination with sodium aluminate. Summary of the invention
[0005] In view of this, the object of the present invention is to provide a method for producing hydrogen by gasification of biochar using calcium oxide in conjunction with sodium aluminate.
[0006] To achieve the above object, a method for hydrogen production by gasification enhanced by calcium oxide and sodium aluminate adsorption-catalysis of the present invention comprises the following steps: (1) pure bamboo charcoal, (2) calcium oxide and bamboo charcoal, (3) sodium aluminate and bamboo charcoal, and (4) calcium oxide, sodium aluminate and bamboo charcoal were placed in a hydrogen production reactor in a certain proportion and combination, and 60% water vapor / nitrogen was introduced to react at a certain temperature for 2 h. In the hydrogen production reactor, biochar and water vapor can react to produce a small amount of hydrogen; calcium oxide can effectively adsorb and react to produce carbon dioxide; sodium aluminate can effectively catalyze the gasification reaction; calcium oxide and sodium aluminate have a synergistic effect, both adsorbing CO2 and catalyzing the reaction, ensuring high hydrogen production and high concentration.
[0007] Preferably, the adsorbent calcium source precursor is at least one of calcium salts such as calcium carbonate, calcium nitrate, and calcium hydroxide.
[0008] Preferably, the catalyst sodium aluminate is at least one of various sodium aluminate forms such as high-purity sodium aluminate, sodium aluminate containing specific impurities, sodium aluminate of different crystal forms, etc. Further preferably, the combination of biochar, calcium oxide and sodium aluminate includes but is not limited to at least one of mixing, loading, incorporating, encapsulating or other effective combination methods; Preferably, the molar ratio of CaO to bamboo charcoal is 0.25 to 1; Preferably, the mass ratio of NaAlO2 to bamboo charcoal is 0.28 to 3.2; The preferred reaction temperature is 600-700°C; Through the cyclic hydrogen production experiment, preferably, NaAlO2 does not react with ash during the hydrogen production process and maintains stability; Compared with the prior art, the present invention has the following advantages and technical effects: it not only increases the hydrogen production and concentration, but also maintains the high activity of the catalyst, while producing high-concentration CO2, which is then sealed and utilized to achieve net negative emissions. BRIEF DESCRIPTION OF THE DRAWINGS
[0009] In order to more clearly illustrate the embodiments of the present invention, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.
[0010] Figure 1 This is a comparison chart of the hydrogen production characteristics of the catalytic gasification of various reactants in the present invention; Figure 2 The graph of hydrogen production and concentration at different molar ratios of calcium oxide and bamboo charcoal of the present invention; Figure 3 The graph of hydrogen production and concentration of sodium aluminate and bamboo charcoal at different mass ratios of the present invention; Figure 4 The graphs of gasification hydrogen production and concentration at different temperatures of the present invention are as follows; Figure 5 This is the XRD analysis diagram of sodium aluminate cyclic hydrogen production in the present invention; Figure 6 This is a graph showing the hydrogen production and concentration after 10 cycles of the present invention; DETAILED DESCRIPTION In order to facilitate the understanding of those skilled in the art, the present invention is further described below in conjunction with specific embodiments and drawings. Three chemical equations are provided below to further understand the present invention.
[0011] Reaction 1 Reaction 2 Reaction 3 According to the above equation, if you want to make the H2 concentration and output higher, you should speed up reaction 1 and fully absorb CO2. Through literature review and experimental verification, NaAlO2 can be used as a catalyst to speed up reactions 1 and 2, and CaO can fully absorb CO2 to make reaction 2 proceed.
[0012] Before submitting the patent application, the present invention has conducted sufficient literature search and duplicate checking to ensure that the proposed technical solution is novel and non-obvious. When describing specific values and ranges, duplication with the disclosures in the prior art has been avoided as much as possible. However, due to the voluminous and complex nature of patent documents, there may be similarities in individual expressions or values, but this does not constitute a negation of the novelty and creativity of the present invention.
[0013] Comparative Example 1 Under the conditions of 0.1 MPa, 650 °C, and 60% water vapor atmosphere, hydrogen is produced by gasification for 2 h. The molar ratio of CaO to bamboo charcoal is preferably 0.5, and the mass ratio of NaAlO2 to bamboo charcoal is preferably 2.8.
[0014] from Figure 1 It can be seen that in the hydrogen production process under pure bamboo charcoal, the H2 production is 42.02mL, CO2 production is 48.74mL, CO production is 3.37mL, CH4 production is 24.98mL and the H2 concentration is 35.28%.
[0015] Comparative Example 2 Compared with Comparative Example 1, the only difference is that calcium oxide is added to the pure bamboo charcoal and the hydrogen production process is carried out.
[0016] Compared with pure bamboo charcoal gasification to produce hydrogen, the gas production was significantly improved after adding CaO, with H2 production of 148.49 mL, CO2 production of 169.26 mL, CO production of 8.42 mL, CH4 production of 65.9 mL and H2 concentration of 37.88%.
[0017] Comparative Example 3 Compared with Comparative Example 1, the only difference is that sodium aluminate is added to the pure bamboo charcoal and the hydrogen production process is carried out.
[0018] from Figure 1 It can be clearly seen that NaAlO2 played an obvious catalytic role, with H2 production of 561.48 mL, total CO2 production of 273.01 mL, CO production of 55.07 mL, CH4 production of 33.72 mL and H2 concentration of 60.81%.
[0019] Comparative Example 4 Compared with Comparative Examples 1, 2 and 3, the only difference is that calcium oxide, sodium aluminate and bamboo charcoal are mixed together and a hydrogen production process is carried out.
[0020] from Figure 1 It can be clearly observed that the H2 production when CaO and NaAlO2 are added is higher than that of bamboo charcoal + CaO and bamboo charcoal + NaAlO2. At this time, the total H2 production is 623.48 mL, the CO2 production is 90.36 mL, the CO production is 19.99 mL, the CH4 production is 12.84 mL, and the H2 concentration is 83.5%.
[0021] By comparing Comparative Examples 1-4, it can be seen that the hydrogen production from pure bamboo charcoal gasification is 42.02 mL, and the total H2 production after adding CaO and NaAlO2 are 148.49 mL and 561.48 mL respectively. When CaO and NaAlO2 are synergistically mixed with bamboo charcoal for catalysis, the total H2 production reaches 623.48 mL and the concentration is greatly improved. Therefore, hydrogen can be efficiently produced through the synergistic effect of calcium oxide and sodium aluminate.
[0022] Example 1 Figure 2 This is a graph of H2 production and concentration at different molar ratios of CaO and bamboo charcoal. The experimental conditions are gasification and hydrogen production for 2 h at 0.1 MPa, 650 °C, and 60% water vapor atmosphere. Only the molar ratio of CaO to bamboo charcoal is changed, and the other conditions remain unchanged.
[0023] When the molar ratio of CaO to bamboo charcoal was 0.25, the H2 production was 588.46 mL, CO2 production was 102.14 mL, CO production was 27.65 mL, CH4 production was 23.06 mL, and the H2 concentration was 79%.
[0024] Example 2 Compared with Example 1, the only difference is that when the molar ratio of CaO to bamboo charcoal is increased to 0.5, the H2 production is 623.48 mL, the CO2 production is 90.36 mL, the CO production is 19.99 mL, the CH4 production is 12.84 mL, and the H2 concentration is 84%.
[0025] Example 3 Compared with Example 2, the only difference is that when the molar ratio of CaO to bamboo charcoal is increased to 1, the H2 production is 496.74 mL, the CO2 production is 79.24 mL, the CO production is 22.47 mL, the CH4 production is 31.72 mL, and the H2 concentration is 79%.
[0026] Through Examples 1-3, in the actual process, a suitable molar ratio of CaO to bamboo charcoal should be selected to meet the needs. The subsequent examples of the present invention preferably use a molar ratio of CaO to bamboo charcoal of 0.5 to study the influence of the mass ratio of NaAlO2 to bamboo charcoal and the gasification temperature.
[0027] Example 4 Figure 3 This is a graph of H2 production and concentration at different mass ratios of NaAlO2 and bamboo charcoal. The experimental conditions are gasification to produce hydrogen for 2 h at 0.1 MPa, 650 °C, and 60% water vapor atmosphere. The molar ratio of CaO to bamboo charcoal is 0.5. Only the mass ratio of NaAlO2 to bamboo charcoal is changed, and the other conditions remain unchanged.
[0028] When the mass ratio of NaAlO2 to bamboo charcoal was 0.28, the H2 production was 255.41 mL, while the CO2 production was 88.59 mL, the CO production was 9.34 mL, the CH4 production was 37.28 mL, and the H2 concentration was 65%.
[0029] Example 5 Same as Example 4, except that the mass ratio of NaAlO2 to bamboo charcoal is 1.6, the H2 production is 548.59 mL, the CO2 production is 96.28 mL, the CO production is 17.24 mL, the CH4 production is 18.89 mL, and the H2 concentration is 80%.
[0030] Example 6 Same as Example 5, except that the mass ratio of NaAlO2 to bamboo charcoal is 2.4, the H2 production is 570.14 mL, the CO2 production is 90.19 mL, the CO production is 19.86 mL, the CH4 production is 13.10 mL, and the H2 concentration is 82%.
[0031] Example 7 Same as Example 6, except that the mass ratio of NaAlO2 to bamboo charcoal is 2.8, the H2 production is 623.48 mL, the CO2 production is 90.36 mL, the CO production is 19.99 mL, the CH4 production is 12.84 mL, and the H2 concentration is 84%.
[0032] Example 8 Same as Example 7, except that the mass ratio of NaAlO2 to bamboo charcoal is 3.2, the H2 production is 593.52 mL, the CO2 production is 90.38 mL, the CO production is 23.88 mL, the CH4 production is 25.89 mL, and the H2 concentration is 81%.
[0033] Through Examples 4-8, in the actual process, a suitable mass ratio of NaAlO2 to bamboo charcoal should be selected to meet the needs. The present invention preferably sets the mass ratio of NaAlO2 to bamboo charcoal to 2.8, and studies the influence of subsequent gasification temperature.
[0034] Example 9 Figure 4 This is a graph of H2 production and concentration at different temperatures. The experimental conditions are gasification to produce hydrogen for 2 h under 0.1 MPa and 60% water vapor atmosphere. The molar ratio of CaO to bamboo charcoal is 0.5, and the mass ratio of NaAlO2 to bamboo charcoal is 2.8. Only the gasification temperature is changed, and the other conditions remain unchanged.
[0035] When the gasification temperature is set to 600 °C, the H2 production is 500.29 mL, CO2 production is 28.79 mL, CO production is 2.82 mL, CH4 production is 20.52 mL, and the H2 concentration is 90%.
[0036] Example 10 Compared with Example 9, the difference is that the gasification temperature is increased to 650°C, the H2 production is 623.48 mL, the CO2 production is 90.36 mL, the CO production is 19.99 mL, the CH4 production is 12.84 mL, and the H2 concentration is 94%.
[0037] Embodiment 11 Compared with Example 10, the difference is that the gasification temperature is increased to 700°C, the H2 production is 939.98 mL, the CO2 production is 232.02 mL, the CO production is 21.11 mL, the CH4 production is 12.53 mL, and the H2 concentration is 78%. It can be concluded from Examples 9-11 that as the temperature increases, the H2 production tends to increase, but the concentration tends to decrease. This shows that the specific temperature should be selected according to the actual process conditions.
[0038] Example 12 The reason why sodium aluminate can maintain catalytic stability during the cyclic hydrogen production process is mainly due to its inherent high stability, which avoids chemical reactions with other components in bamboo charcoal.
[0039] In order to verify the catalytic stability of sodium aluminate in the hydrogen production process, the present invention extracts samples of the first and tenth cycles of sodium aluminate in the cyclic hydrogen production process.
[0040] The reaction conditions are: gasification hydrogen production for 2 h under 0.1MPa, 650℃, and 60% water vapor atmosphere, the molar ratio of CaO to bamboo charcoal is 0.5, the mass ratio of NaAlO2 to bamboo charcoal is 2.8, and the hydrogen production process is cyclic. After each independent hydrogen production process, bamboo charcoal needs to be added at the beginning of a new hydrogen production process to ensure that the quality of bamboo charcoal remains constant during the hydrogen production process. Since the output of CO and CH4 in the hydrogen production process is not high and the change is not obvious, the two are not studied.
[0041] The present invention has carried out XRD test ( Figure 5 ), it can be clearly seen from the XRD spectrum that after the 10th cycle, the hydrogen production process produced new substances Ca2SiO4, Ca2Fe7O 11 and CaFeO3, are mainly caused by the reaction of the adsorbent calcium oxide with elements such as Si and Fe in the ash. However, NaAlO2 has no significant change before and after the cyclic hydrogen production and remains stable.
[0042] The present invention produces hydrogen through 10 cycles ( Figure 6 ), with the increase of cycle number, the H2 concentration remained basically stable (about 80%), and the H2 production was basically maintained at around 600 mL.
[0043] NaAlO2 exhibits good stability throughout the entire cycle, thanks to its chemical stability and inertness to bamboo charcoal ash, thus maintaining high stability during the hydrogen production process. At the same time, the present invention strongly confirms the stability and reliability of NaAlO2 as a hydrogen production catalyst through XRD analysis of sodium aluminate and the yield and concentration of cyclic hydrogen production.
Claims
1. A method for enhancing hydrogen production by biochar gasification using calcium oxide and sodium aluminate adsorption-catalysis, characterized in that: The invention comprises an adsorbent calcium oxide, a catalyst sodium aluminate and suitable biochar as reactants. The specific method comprises the following steps: placing calcium oxide, sodium aluminate and biochar in a certain proportion into a hydrogen production reactor and introducing water vapor, wherein the calcium oxide adsorbs CO2 produced by the gasification reaction and the sodium aluminate catalyzes the gasification reaction. The two act synergistically to ensure the stability of the sodium aluminate at a certain temperature while also increasing the concentration and output of hydrogen production.
2. The method for producing hydrogen by gasification using calcium oxide in coordination with sodium aluminate adsorption-catalysis enhancement according to claim 1, characterized in that: The calcium oxide includes but is not limited to calcium oxide prepared from calcium-based precursors such as calcium carbonate, calcium nitrate, and calcium hydroxide.
3. The method for producing hydrogen by gasification using calcium oxide in coordination with sodium aluminate adsorption-catalysis enhancement according to claim 1, characterized in that: The sodium aluminate includes, but is not limited to, various forms of sodium aluminate such as high-purity sodium aluminate, sodium aluminate containing specific impurities, and sodium aluminate in different crystal forms.
4. The method for producing hydrogen by gasification using calcium oxide in coordination with sodium aluminate adsorption-catalysis enhancement according to claim 1, characterized in that: The method is implemented by using a combination of biochar, calcium oxide and sodium aluminate, including but not limited to mixing, loading, incorporating, encapsulating or other effective combinations.
5. The method for producing hydrogen by gasification using calcium oxide in coordination with sodium aluminate adsorption-catalysis enhancement according to claim 1, characterized in that: The molar ratio of calcium oxide to biochar is 0.25-1.
6. The method for producing hydrogen by gasification using calcium oxide in coordination with sodium aluminate adsorption-catalysis enhancement according to claim 1, characterized in that: The mass ratio of sodium aluminate to biochar is between 0.28 and 3.
2.
7. The method for producing hydrogen by gasification using calcium oxide in coordination with sodium aluminate adsorption-catalysis enhancement according to claim 1, characterized in that: The certain temperature is between 600 and 700°C.
8. The method for producing hydrogen by gasification using calcium oxide in coordination with sodium aluminate adsorption-catalysis enhancement according to claim 1, characterized in that: Under the synergistic effect, sodium aluminate does not react with the ash in the biochar, thereby maintaining its stability.