AU2017100489A4 - Composite catalyst for preparing hydrogen by supercritical water gasification of low-moisture-content dehydrated sludge and use of composite catalyst - Google Patents
Composite catalyst for preparing hydrogen by supercritical water gasification of low-moisture-content dehydrated sludge and use of composite catalyst Download PDFInfo
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- AU2017100489A4 AU2017100489A4 AU2017100489A AU2017100489A AU2017100489A4 AU 2017100489 A4 AU2017100489 A4 AU 2017100489A4 AU 2017100489 A AU2017100489 A AU 2017100489A AU 2017100489 A AU2017100489 A AU 2017100489A AU 2017100489 A4 AU2017100489 A4 AU 2017100489A4
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
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- Y02P20/50—Improvements relating to the production of bulk chemicals
- Y02P20/54—Improvements relating to the production of bulk chemicals using solvents, e.g. supercritical solvents or ionic liquids
Abstract
A composite catalyst for preparing hydrogen by supercritical water gasification of low-moisture-content dewatered sewage sludge and a use of the composite catalyst are disclosed. The catalyst comprises the following raw materials in parts by weight: 50 to 75 parts of active nickel and 25 to 50 parts of a carbon fixation agent, wherein the carbon fixation agent is one of NaOH, KOH, Ca(OH)2, CaO, CaSiO 3 and Na 2SiO 3. The catalyst can be used for catalyzing hydrogen production from low-moisture-content dehydrated sludge at a relatively low reaction temperature, the catalytic efficiency is high, and the costs are saved.
Description
1 2017100489 04 May 2017
COMPOSITE CATALYST FOR PREPARING HYDROGEN BY SUPERCRITICAL WATER GASIFICATION OF LOW-MOISTURE-CONTENT DEHYDRATED SLUDGE AND USE OF
COMPOSITE CATALYST
BACKGROUND OF THE INVENTION
Field of the Invention
The present invention relates to the field of composite catalysts for preparing hydrogen by supercritical water gasification of dehydrated sludge, and more particularly, to a composite catalyst for preparing hydrogen by supercritical water gasification of low-moisture-content dehydrated sludge and a use of the composite catalyst.
Description of Related Process
The production of sludge, as the end product of sewage treatment of sewage plants, increases year by year. The sludge has high moisture content, and its composition is complicated. The sludge not only contains a large amount of organic matters, and nutrients such as nitrogen and phosphorus, but also contains pathogenic bacteria, heavy metals, persistent organic pollutants, and the like. Improper treatment and disposal of the sludge may severely damage the environment. Therefore, how to implement harmless disposal, reduction, and reclamation of the sludge becomes a focus of researchers. The supercritical water gasification treatment technology is paid much attention by scholars as it allows direct feeding of wet sludge without any predrying treatment and is also capable of transforming organic substances in the sludge into clean energy such as hydrogen for use.
For example, a Chinese Patent with the application No. 200810063091.8 disclosed a method for preparing hydrogen-rich gas by continuous catalytic gasification of sludge in supercritical water. The technical solution used in the patent is heating and pressurizing sludge and water respectively and then injecting the heated and pressurized sludge and water into a reactor at a certain ratio. From the perspective 2 2017100489 04 May 2017 of sludge treatment, since additional water is added to formulate a slurry, the sludge treatment efficiency is reduced, and also the formulation procedure and the costs are additionally increased. However, sludge of sewage plants in China is generally dehydrated sludge following a dehydration treatment (having a moisture content of about 80%), and direct supercritical water gasification of low-moisture-content dehydrated sludge to generate hydrogen can greatly reduce the scale of treatment facilities and greatly improve the treatment efficiency and energy efficiency. A Chinese Patent with the application No. 201210205415.3 disclosed an apparatus and a method for direct supercritical water gasification treatment of low-moisture-content dehydrated sludge. However, in the process of direct supercritical water gasification treatment using low-moisture-content dehydrated sludge, coke may be generated and gasification may be inhibited, resulting in low gas production and low hydrogen production and thus poor energy utilization.
Therefore, it is critical for technical applications to select or develop a suitable catalyst for improving the hydrogen production. However, currently, there is a lack of an efficient catalyst suitable for hydrogen production from low-moisture-content dehydrated sludge.
SUMMARY OF THE INVENTION
Technical problem to be solved: An objective of the present invention is, to overcome the defects of the prior process, provide a composite catalyst for preparing hydrogen by supercritical water gasification of low-moisture-content dehydrated sludge and a use of the composite catalyst. The composite catalyst has a good application prospect in the process of preparing hydrogen by supercritical water gasification of low-moisture-content dehydrated sludge, and can achieve efficient catalytic effect in a low-temperature condition to prepare a hydrogen-rich gas.
Technical solution of the present invention: A composite catalyst for preparing hydrogen by supercritical water gasification of low-moisture-content dehydrated sludge, including the following raw materials in parts by weight: 50 to 75 parts of active nickel and 25 to 50 parts of a carbon fixation agent, where the carbon fixation agent is one of NaOH, KOH, Ca(OH)2, CaO, CaSiC>3 and Na2SiC>3. 3 2017100489 04 May 2017
The composite catalyst for preparing hydrogen by supercritical water gasification of low-moisture-content dehydrated sludge, further including no more than 20 parts by weight of an alkali salt.
The composite catalyst for preparing hydrogen by supercritical water gasification of low-moisture-content dehydrated sludge, wherein the alkali salt is present in an amount of no more than 10 parts by weight.
The composite catalyst for preparing hydrogen by supercritical water gasification of low-moisture-content dehydrated sludge according to any of the items above, wherein the active nickel is Raney nickel or reduced nickel powder.
The composite catalyst for preparing hydrogen by supercritical water gasification of low-moisture-content dehydrated sludge, wherein the alkali salt is K2CO3, Na2CC>3, orNaHC03. A use of the composite catalyst for preparing hydrogen by supercritical water gasification of low-moisture-content dehydrated sludge in a process of supercritical water gasification of low-moisture-content dehydrated sludge, characterized in that the dehydrated sludge is added to a liquefaction device, and is kept in a condition of 250-350°C and 5-15 Mpa for 30-60 min; a solid-liquid mixture after liquefaction is subjected to solid-liquid separation to obtain a liquid-phase product; the composite catalyst is added to the liquid-phase product and uniformly mixed; and then the mixture is fed into a supercritical reaction device, wherein the added composite catalyst is 2%-10% of the total amount of the dehydrated sludge.
The use of the composite catalyst for preparing hydrogen by supercritical water gasification of low-moisture-content dehydrated sludge in a process of supercritical water gasification of low-moisture-content dehydrated sludge, wherein the moisture content of the low-moisture-content dehydrated sludge is 74%-88%, and the reaction temperature of the supercritical reaction is 400-500°C.
The composite catalyst for preparing hydrogen by supercritical water gasification of low-moisture-content dehydrated sludge according to the present invention is obtained by uniformly mixing the raw materials in the ratio by weight.
Beneficial effects:
Compared with the prior process, the present invention has the following 4 2017100489 04 May 2017 advantages:
First, the composite catalyst in the present invention is specially developed for low hydrogen production of low-moisture-content dehydrated sludge, and can effectively promote gasification, improve the gasification efficiency, and reduce the coke content, the catalytic efficiency is high and the operations are simple.
Second, by using the composite catalyst, a hydrogen-rich gas having a hydrogen content of up to 88% may be generated at an added amount of 5%, the hydrogasification efficiency is effectively improved, and a significant catalytic effect is achieved.
Third, the composite catalyst can catalyze hydrogen production from the low-moisture-content dehydrated sludge at a low reaction temperature (400°C), the catalytic efficiency is high, and the costs are greatly saved.
BRIEF DESCRIPTION OF THE DRAWINGS
DETAILED DESCRIPTION OF THE INVENTION
The present invention is further described below in detail with reference to embodiments.
Example 1 A composite catalyst for preparing hydrogen by supercritical water gasification of low-moisture-content dehydrated sludge includes the following raw materials in parts by weight: 75 parts of reduced nickel powder and 25 parts of NaOH.
Example 2 A composite catalyst for preparing hydrogen by supercritical water gasification of low-moisture-content dehydrated sludge includes the following raw materials in parts by weight: 50 parts of reduced nickel powder and 50 parts of NaOH.
Example 3 A composite catalyst for preparing hydrogen by supercritical water gasification of 5 2017100489 04 May 2017 low-moisture-content dehydrated sludge includes the following raw materials in parts by weight: 50 parts of Raney nickel and 50 parts of KOH.
Example 4 A composite catalyst for preparing hydrogen by supercritical water gasification of low-moisture-content dehydrated sludge includes the following raw materials in parts by weight: 50 parts of reduced nickel powder and 50 parts of CaO.
Example 5 A composite catalyst for preparing hydrogen by supercritical water gasification of low-moisture-content dehydrated sludge includes the following raw materials in parts by weight: 50 parts of reduced nickel powder and 50 parts of Na2Si03.
Example 6 A composite catalyst for preparing hydrogen by supercritical water gasification of low-moisture-content dehydrated sludge includes the following raw materials in parts by weight: 55 parts of reduced nickel powder, 25 parts of KOH, and 20 parts of
Na2C03.
Example 7 A composite catalyst for preparing hydrogen by supercritical water gasification of low-moisture-content dehydrated sludge includes the following raw materials in parts by weight: 50 parts of reduced nickel powder, 40 parts of NaOH, and 10 parts of K2CO3.
Example 8 A composite catalyst for preparing hydrogen by supercritical water gasification of low-moisture-content dehydrated sludge includes the following raw materials in parts by weight: 50 parts of Raney nickel, 40 parts of Ca(OH)2, and 10 parts of NaHCC>3.
Example 9 A composite catalyst for preparing hydrogen by supercritical water gasification of low-moisture-content dehydrated sludge includes the following raw materials in parts by weight: 60 parts of reduced nickel powder, 30 parts of CaO, and 10 parts of K2CO3.
Example 10 6 2017100489 04 May 2017 A composite catalyst for preparing hydrogen by supercritical water gasification of low-moisture-content dehydrated sludge includes the following raw materials in parts by weight: 60 parts of reduced nickel powder, 30 parts of Na2Si03, and 10 parts of NaHC03.
Example 11 A composite catalyst for preparing hydrogen by supercritical water gasification of low-moisture-content dehydrated sludge includes the following raw materials in parts by weight: 55 parts of Raney nickel, 25 parts of CaSiC>3, and 20 parts of K2CO3.
Application example 1
The object being treated is dehydrated sludge (having a moisture content of 77.05%) of a sewage plant in Nanjing, Jiangsu, the reaction temperature is 400°C and the reaction time is 10 min, and an added amount of a catalyst is 5% of the total weight of the dehydrated sludge. Changes in the composition of a gas-phase product before and after a composite catalyst is added are shown.
Serial No. Composition of the catalyst (parts) Gas-phase composition (%) Active nickel Carbon fixation agent Alkali salt h2 CO ch4 C02 1 Without catalyst 19.79 2.84 5.46 71.91 2 75 parts reduced nickel 25 parts NaOH 77.64 3.41 5.72 13.23 3 50 parts reduced nickel 50 parts NaOH 80.41 4.45 8.49 6.64 4 50 parts Raney nickel 50 parts KOH 84.16 3.96 6.93 4.95 5 50 parts reduced nickel 50 parts CaO 46.88 5.21 11.46 36.46 6 50 parts reduced nickel 50 parts Na2Si03 39.49 6.97 13.26 40.28 7 55 parts reduced nickel 25 parts KOH 20 parts Na2C03 79.01 4.21 5.03 11.75 8 50 parts reduced nickel 40 parts NaOH 10 parts K2C03 88.09 3.62 6.40 1.88 9 50 parts Raney nickel 40 parts Ca(OH)2 10 parts NaHCOs 72.33 3.38 5.98 18.30 10 60 parts reduced nickel 30 parts CaO 10 parts K2C03 53.91 5.06 10.40 30.63 11 60 parts reduced 30 parts Na2Si03 10 parts NaHC03 46.01 5.32 11.98 36.69 7 nickel 12 55 parts Raney nickel 25 parts CaSi03 20 parts K2CO3 53.80 6.20 7.64 32.36
It can be seen from the above table that, when no catalyst is added, the hydrogen content in the gas after direct supercritical water gasification of the dehydrated sludge is merely 20%; and after the composite catalyst in the present invention is added, the hydrogen content in the gas after the reaction is about 39%-88%, which is much higher than that when no catalyst is added, indicating that the composite catalyst has a significant effect on improvement of the hydrogen content. Further, addition of the carbon fixation agent can significantly reduce the content of carbon dioxide in the gas, from the original 71% to 40%-2%, which significantly increases the purity of hydrogen in the gas. Moreover, addition of the alkali salt in the composite catalyst provides a better effect than that when no alkali salt is added, and can improve the hydrogen content by about 5% to 10%. Among the selected carbon fixation agents, NaOH has a better effect, and among the alkali salts, K2CO3 has a better effect. 2017100489 04 May 2017
Application example 2
The objects being treated are dehydrated sludges of 4 different sewage plants in Suzhou, Jiangsu, the reaction temperature is 400°C and the reaction time is 10 min, and an added amount of a catalyst is 5% of the total weight of the dehydrated sludge. Changes in the composition of a gas-phase product before and after a composite catalyst is added are shown, and the percentage of hydrogen is significantly improved.
Serial No. Moisture content (%) Composition of the catalyst (parts) Gas-phase composition (%) Active nickel Carbon fixation agent Alkali salt h2 CO ch4 C02 1 77.91 Without catalyst 2.04 0.53 0.35 97.08 50 parts reduced nickel 50 parts NaOH 37.27 1.50 2.65 58.57 50 parts reduced nickel 40 parts NaOH 10 parts K2C03 42.71 1.42 2.50 53.37 2 87.75 Without catalyst 8.07 8.17 10.53 73.23 50 parts reduced nickel 50 parts NaOH 55.99 5.51 7.12 31.38 50 parts reduced nickel 40 parts NaOH 10 parts K2C03 57.46 3.03 5.46 34.05 3 88.51 Without catalyst 15.91 1.92 7.95 74.22 50 parts |50 parts NaOH| 57.47 13.25 10.96 18.32 8 reduced nickel 50 parts reduced nickel 40 parts NaOH 10 parts K2C03 60.45 5.00 7.58 26.97 4 86.29 Without catalyst 7.34 1.49 2.05 89.12 50 parts reduced nickel 50 parts NaOH 74.93 4.63 15.30 5.14 50 parts reduced nickel 40 parts NaOH 10 parts K2C03 75.08 3.29 8.61 13.02 2017100489 04 May 2017
The sludge is complex in nature, and dehydrated sludges of different sewage plants are very different in nature. In order to determine whether the selected composite catalysts have good catalytic effect on dehydrated sludges of different natures, 4 dehydrated sludges from Suzhou are selected for comparison. The selected dehydrated sludges have a moisture content of between 77.91% and 88.51% and an organic content of between 29.25% and 63.94%. The results are shown in the above table, indicating that the composite catalysts listed in the present invention all have good catalytic effect on the dehydrated sludges in the above nature scope, and the percentage of hydrogen is increased by about 4 to 21 times. Similarly, the catalytic effect with addition of the alkali salt is slightly better. This indicates that the composite catalyst for preparing hydrogen by supercritical water gasification of low-moisture-content dehydrated sludge shown in the present invention has a certain generality, and may have a promoting effect on the hydrogen production from dehydrated sludges of other natures.
Claims (7)
- The claims defining the invention are as follows:1. A composite catalyst for preparing hydrogen by supercritical water gasification of low-moisture-content dehydrated sludge, comprising the following raw materials in parts by weight: 50 to 75 parts of active nickel and 25 to 50 parts of a carbon fixation agent, wherein the carbon fixation agent is one of NaOH, KOH, Ca(OH)2, CaO, CaSiC>3, and Na2SiC>3.
- 2. The composite catalyst for preparing hydrogen by supercritical water gasification of low-moisture-content dehydrated sludge according to claim 1, further comprising no more than 20 parts by weight of an alkali salt.
- 3. The composite catalyst for preparing hydrogen by supercritical water gasification of low-moisture-content dehydrated sludge according to claim 2, wherein the alkali salt is present in an amount of no more than 10 parts by weight.
- 4. The composite catalyst for preparing hydrogen by supercritical water gasification of low-moisture-content dehydrated sludge according to claim 1, 2, or 3, wherein the active nickel is Raney nickel or reduced nickel powder.
- 5. The composite catalyst for preparing hydrogen by supercritical water gasification of low-moisture-content dehydrated sludge according to claim 2 or 3, wherein the alkali salt is K2CO3, Na2CC>3, or NaHCC>3.
- 6. A use of the composite catalyst for preparing hydrogen by supercritical water gasification of low-moisture-content dehydrated sludge according to claim 1 in a process of supercritical water gasification of low-moisture-content dehydrated sludge, wherein the dehydrated sludge is added to a liquefaction device, and is kept in a condition of 250-350°C and 5-15 Mpa for 30-60 min; a solid-liquid mixture after liquefaction is subjected to solid-liquid separation to obtain a liquid-phase product; the composite catalyst is added to the liquid-phase product and uniformly mixed; and then the mixture is fed into a supercritical reaction device, wherein the added composite catalyst is 2%-10% of the total amount of the dehydrated sludge.
- 7. The use of the composite catalyst for preparing hydrogen by supercritical water gasification of low-moisture-content dehydrated sludge in a process of supercritical water gasification of low-moisture-content dehydrated sludge according to claim 6, wherein the moisture content of the low-moisture-content dehydrated sludge is 74%-88%, and the reaction temperature of the supercritical reaction is 400-500°C.
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| AU2017100489A AU2017100489A4 (en) | 2014-12-17 | 2017-05-04 | Composite catalyst for preparing hydrogen by supercritical water gasification of low-moisture-content dehydrated sludge and use of composite catalyst |
Applications Claiming Priority (4)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201410787669.XA CN104502047A (en) | 2014-12-17 | 2014-12-17 | Experimental facility and experimental method for verifying aseismic design of spherical tank |
| CN201410787698.6 | 2014-12-17 | ||
| PCT/CN2015/082494 WO2016095478A1 (en) | 2014-12-17 | 2015-06-26 | Composite catalyst for preparing hydrogen by supercritical water gasification of low-moisture-content dehydrated sludge and application of composite catalyst |
| AU2017100489A AU2017100489A4 (en) | 2014-12-17 | 2017-05-04 | Composite catalyst for preparing hydrogen by supercritical water gasification of low-moisture-content dehydrated sludge and use of composite catalyst |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| PCT/CN2015/082494 Division WO2016095478A1 (en) | 2014-12-17 | 2015-06-26 | Composite catalyst for preparing hydrogen by supercritical water gasification of low-moisture-content dehydrated sludge and application of composite catalyst |
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| AU2017100489A4 true AU2017100489A4 (en) | 2017-06-01 |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN117046403A (en) * | 2023-10-11 | 2023-11-14 | 天津高能时代水处理科技有限公司 | Tower type fluidization reactor with airlift power high-magnification reflux and staggered baffling mixing |
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- 2017-05-04 AU AU2017100489A patent/AU2017100489A4/en not_active Ceased
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN117046403A (en) * | 2023-10-11 | 2023-11-14 | 天津高能时代水处理科技有限公司 | Tower type fluidization reactor with airlift power high-magnification reflux and staggered baffling mixing |
| CN117046403B (en) * | 2023-10-11 | 2024-01-23 | 天津高能时代水处理科技有限公司 | Tower type fluidization reactor with airlift power high-magnification reflux and staggered baffling mixing |
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