WO2020103330A1 - 蜂窝式低温scr脱硝催化剂及其制备方法 - Google Patents

蜂窝式低温scr脱硝催化剂及其制备方法

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WO2020103330A1
WO2020103330A1 PCT/CN2019/072898 CN2019072898W WO2020103330A1 WO 2020103330 A1 WO2020103330 A1 WO 2020103330A1 CN 2019072898 W CN2019072898 W CN 2019072898W WO 2020103330 A1 WO2020103330 A1 WO 2020103330A1
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parts
scr denitration
denitration catalyst
met
takes
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PCT/CN2019/072898
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English (en)
French (fr)
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高春昱
孟凡强
秦一鸣
王建国
陈华
于宁
范娟
孙文强
徐海龙
贺明洁
王金峰
刘莉
张鑫
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华电青岛环保技术有限公司
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Publication of WO2020103330A1 publication Critical patent/WO2020103330A1/zh

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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J23/00—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00
    • B01J23/16—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of arsenic, antimony, bismuth, vanadium, niobium, tantalum, polonium, chromium, molybdenum, tungsten, manganese, technetium or rhenium
    • B01J23/24—Chromium, molybdenum or tungsten
    • B01J23/30—Tungsten
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
    • B01D53/34—Chemical or biological purification of waste gases
    • B01D53/74—General processes for purification of waste gases; Apparatus or devices specially adapted therefor
    • B01D53/86—Catalytic processes
    • B01D53/8621—Removing nitrogen compounds
    • B01D53/8625—Nitrogen oxides
    • B01D53/8628—Processes characterised by a specific catalyst
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
    • B01D53/34—Chemical or biological purification of waste gases
    • B01D53/74—General processes for purification of waste gases; Apparatus or devices specially adapted therefor
    • B01D53/86—Catalytic processes
    • B01D53/90—Injecting reactants
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J37/00—Processes, in general, for preparing catalysts; Processes, in general, for activation of catalysts
    • B01J37/08—Heat treatment
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2255/00—Catalysts
    • B01D2255/20—Metals or compounds thereof
    • B01D2255/207—Transition metals
    • B01D2255/20707—Titanium
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2255/00—Catalysts
    • B01D2255/20—Metals or compounds thereof
    • B01D2255/207—Transition metals
    • B01D2255/20723—Vanadium
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2255/00—Catalysts
    • B01D2255/20—Metals or compounds thereof
    • B01D2255/207—Transition metals
    • B01D2255/20769—Molybdenum
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2255/00—Catalysts
    • B01D2255/20—Metals or compounds thereof
    • B01D2255/207—Transition metals
    • B01D2255/20776—Tungsten
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2255/00—Catalysts
    • B01D2255/30—Silica

Definitions

  • the invention relates to a honeycomb low-temperature SCR denitration catalyst and a preparation method thereof, which belong to the technical field of flue gas denitration.
  • honeycomb low-temperature SCR denitration catalysts often requires the addition of molybdenum to improve the low-temperature performance of the catalyst.
  • the addition of molybdenum is closely related to the catalyst production process.
  • honeycomb low-temperature SCR denitration catalyst There are two main ways to produce honeycomb low-temperature SCR denitration catalyst: coating method and mixed extrusion method.
  • the coating method is based on a pre-treated honeycomb ceramic (such as cordierite) as a substrate, and a particulate catalyst is coated on the surface, and then dried and roasted to obtain a catalyst. Such catalysts have high strength and wear resistance, but few active components.
  • the mixed extrusion method is to add suitable additives to the prepared granular catalyst, and then go through a series of molding processes to obtain the final desired catalyst.
  • the mixed extrusion method can obtain a homogeneous honeycomb low-temperature SCR denitration catalyst, which is full of active components.
  • the homogeneous honeycomb low-temperature SCR denitration catalyst has high mechanical strength and many active components, and has parallel channels with a large opening rate, which is easy for flue gas to pass through and is less prone to blockage of the catalyst. Because of its excellent performance, the homogeneous honeycomb low-temperature SCR denitration catalyst is the most widely used.
  • the honeycomb low-temperature SCR denitration catalyst has excellent performance, at present, the honeycomb low-temperature SCR denitration catalyst with a high molybdenum content still needs to be produced by the coating method. It is difficult to form in the wet billet extrusion stage.
  • the present invention proposes a new honeycomb low-temperature SCR denitration catalyst and a preparation method thereof.
  • a method for preparing a honeycomb low-temperature SCR denitration catalyst includes the following steps:
  • the weight part is 100-150 parts titanium molybdenum powder, 8-20 parts carboxymethyl cellulose, 5-10 parts polyethylene oxide, 5-7.5 parts silica powder, 5-7.5 parts silicon Sol, 7-18 parts wood pulp, 25-50 parts glass fiber, 50-80 parts deionized water, 5-15 parts ammonium metavanadate solution, 10-20 parts ammonium metatungstate solution, 30-55 parts ammonia water and 10-20 parts of lactic acid is added to the kneading machine and mixed thoroughly; after mixing, the water vapor in the kneading machine is extracted; the moisture content of the material obtained after dehumidification is 25% -30%.
  • the molybdenum content in the titanium molybdenum powder is ⁇ 7%.
  • Molding The material obtained by mixing and mixing is filtered and put into an extruder, which is extruded to obtain a wet billet.
  • the cost of the wet billet can be 80% or more.
  • the content of molybdenum in the titanium-molybdenum powder used in the present invention is ⁇ 7%.
  • the SCR denitration catalyst is prepared by using the hybrid extrusion method, once the content of molybdenum is too high, it is difficult to form.
  • the invention adds silica sol in a mixed manner, which can reduce the specific surface area of the powder after mixing, so that the mixed materials can be extruded smoothly.
  • the higher the content of molybdenum the better the low-temperature performance of the obtained honeycomb low-temperature SCR denitration catalyst, and the catalyst obtained by using the method has better low-temperature performance.
  • the proportion ratio of titanium molybdenum powder and silica sol should be 20: 1, which cannot be adjusted at will, otherwise the molding effect will be poor, or even impossible to mold.
  • step C includes the following small steps:
  • step D includes the following small steps:
  • Heating up phase It takes 14-18 hours. During this period, the heating up conditions are met: the ambient temperature rises from room temperature to 530 ° C, and the air flux is maintained at -20Pa;
  • Cooling stage It takes 7-9 hours. During this period, the cooling conditions are met: the ambient temperature drops from 530 ° C to room temperature.
  • the calcination temperature of the honeycomb low-temperature SCR denitration catalyst produced by the mixed extrusion method is above 600 °C. Once the calcination temperature is lower than 600 °C, the mechanical strength of the obtained catalyst cannot be guaranteed. The middle is extremely fragile. However, the higher the calcination temperature, the higher the energy consumption and the lower the specific surface area of the catalyst. In the present invention, silica sol is added in the mixing stage. Although it is more helpful for extrusion molding, the specific surface area of the powder after mixing is lower. Therefore, in order to obtain a catalyst with high denitration efficiency, it is necessary to try to increase the specific surface area of the material in the subsequent steps.
  • the present application reduces the air flow rate, increasing the air flow rate from the conventional -30Pa to -20Pa, reducing the amount of inhaled oxygen and reducing the catalyst At the degree of sintering during calcination, a larger specific surface area is obtained.
  • the addition of silica powder and silica sol can improve the mechanical strength of the catalyst.
  • the macromolecules of silicon can inhibit the sintering of the catalyst while ensuring the physical properties after low-temperature calcination. The catalyst will not break due to the failure of the physical properties during use. problem.
  • silica powder and silica sol it was found that even if calcined at a temperature of 530 ° C, a catalyst with acceptable mechanical strength can be obtained, reducing energy consumption.
  • step a) includes the following stages:
  • the first stage It takes 3-4 days. During this period, the drying conditions are met: the ambient temperature rises from 30 ° C to 40 ° C, the air supply frequency increases from 15Hz to 30Hz, and the air humidity decreases from 80% to 70%;
  • the second stage It takes 3-4 days. During this period, the drying conditions are met: the ambient temperature rises from 40 ° C to 60 ° C, the air supply frequency increases from 30Hz to 40Hz, and the air humidity decreases from 70% to 40%;
  • the third stage It takes 2-3 days. During this period, the drying conditions are met: the ambient temperature rises from 60 ° C to 70 ° C, the air supply frequency increases from 40Hz to 60Hz, and the air humidity decreases from 40% to 10%.
  • step c) includes the following stages:
  • the first heating stage it takes 7-9 hours. During this period, the heating conditions are met: the ambient temperature rises from room temperature to 300 ° C, and the air flow rate decreases from normal pressure to -20Pa;
  • the second heating stage it takes 7-9 hours. During this period, the heating conditions are met: the ambient temperature rises from 300 ° C to 530 ° C, and the air intake is maintained at -20Pa.
  • an extrusion die is used for extrusion molding, and the surface of the extrusion die is treated with electroless nickel plating.
  • Electroless nickel plating increases the smoothness of the die surface, the extrusion process is smoother, and the extruded wet billet is smoother.
  • the slit width of the extrusion die used in the step B can be adjusted by adjusting the thickness of the nickel plating layer. If a larger slit width is required, only a thinner nickel layer needs to be plated during the extrusion die preparation process, and if a smaller slit width is required, only a thicker nickel layer needs to be plated during the extrusion die preparation process Floor.
  • honeycomb low-temperature SCR denitration catalyst prepared by the method of the invention.
  • honeycomb low-temperature SCR denitration catalyst with high molybdenum content was successfully prepared by the mixed extrusion method, which solved the problem that the material with high molybdenum content is not easy to be formed during the wet blank extrusion stage.
  • the calcination temperature is reduced, so that it still has qualified mechanical strength at a temperature of 530 °C, saving energy consumption.
  • the denitration efficiency of the prepared honeycomb low-temperature SCR denitration catalyst at a temperature of 160-250 ° C reaches more than 83%.
  • a honeycomb low-temperature SCR denitration catalyst includes the following steps:
  • Molding The material obtained by mixing is filtered and put into an extruder, which is extruded to obtain a wet billet; in this step, the surface of the extrusion die is treated with chemical nickel plating, and the thickness of the nickel layer is 100 ⁇ m on one side.
  • the exit slit width is 0.8mm.
  • Drying Put the wet billet into the drying equipment for drying to obtain the dried billet; including the following small steps: one-time drying: takes 8 days, during this period, the drying conditions are met: the ambient temperature rises from 30 °C to 70 °C, The air supply frequency increases from 15 Hz to 50 Hz, and the air humidity decreases from 80% to 10%; when the ambient temperature naturally drops to 35 ° C, the secondary drying is performed: it takes 14 hours. During this period, the drying conditions are met: the ambient temperature is from 35 °C rose to 60 °C.
  • Calcination Put the dried green body into the calcination equipment for calcination to obtain a honeycomb low-temperature SCR denitration catalyst. It includes the following small steps: heating stage: it takes 14 hours. During this period, the heating conditions are met: the ambient temperature rises from room temperature to 530 ° C, and the air intake decreases from normal pressure to -20Pa; the cooling stage: it takes 7 hours, During this period, the cooling conditions are met: the ambient temperature drops from 530 ° C to room temperature. Get catalyst one.
  • a honeycomb low-temperature SCR denitration catalyst includes the following steps:
  • Molding The material obtained by mixing is filtered and put into an extruder, which is extruded to obtain a wet billet; in this step, the surface of the extrusion die is treated with chemical nickel plating, and the thickness of the nickel layer is 100 ⁇ m on one side.
  • the exit slit width is 0.8mm. .
  • Drying Put the wet billet into the drying equipment for drying to obtain the dried billet; including: Primary drying: the first stage: takes 4 days, during which the drying conditions are met: the ambient temperature rises from 30 °C to 40 °C , The air supply frequency increases from 15 Hz to 30 Hz, and the air humidity decreases from 80% to 70%; the second stage: it takes 3 days, during this period, the drying conditions are met: the ambient temperature rises from 40 °C to 60 °C, the air supply frequency From 30Hz to 40Hz, the air humidity drops from 70% to 40%; the third stage: it takes 2 days, during this period, the drying conditions are met: the ambient temperature rises from 60 ° C to 70 ° C, and the air supply frequency increases from 40Hz to At 60 Hz, the air humidity drops from 40% to 10%. When the ambient temperature naturally drops to 35 ° C, secondary drying is performed: it takes 14 hours, during which the drying conditions are met: the ambient temperature rises from 35 ° C to 60 ° C.
  • Calcination Put the dried green body into the calcination equipment for calcination to obtain a honeycomb low-temperature SCR denitration catalyst.
  • the heating up phase including the following phases: the first heating up phase: it takes 8 hours, during this period, the heating up conditions are met: the ambient temperature rises from room temperature to 300 ° C, and the air intake decreases from normal pressure to -20Pa; second Heating phase: it takes 8 hours, during this period, the heating conditions are met: the ambient temperature rises from 300 ° C to 530 ° C, and the air flow is maintained at -20Pa; cooling stage: it takes 8 hours, during which the cooling conditions are met : The ambient temperature drops from 530 ° C to room temperature. Get catalyst two.
  • Embodiment 2 The difference from Embodiment 2 is that the silica powder and silica sol are not added in the kneading stage, and the other steps in the kneading stage are completely the same and cannot be formed.
  • Example 2 The difference from Example 2 is that the amount of silica sol added is 10 parts, and the other steps are exactly the same. Get catalyst three.
  • Example 2 The difference from Example 2 is that the addition amount of silica sol is 3 parts, and the other steps in the kneading stage are completely the same and cannot be molded.
  • the temperature raising stage includes the following stages: the first temperature raising stage: it takes 8 hours, during which the temperature raising conditions are met: the ambient temperature rises from room temperature to 300 ° C, and the air flow rate decreases from atmospheric pressure To -30Pa; the second heating stage: it takes 8 hours. During this period, the heating conditions are met: the ambient temperature rises from 300 ° C to 600 ° C, and the air intake is maintained at -30Pa; the cooling stage: it takes 8 hours, at During this period, the cooling conditions are met: the ambient temperature drops from 600 ° C to room temperature. The other steps are exactly the same. Get catalyst four.
  • the temperature raising stage includes the following stages: the first temperature raising stage: it takes 8 hours, during which the temperature raising conditions are met: the ambient temperature rises from room temperature to 300 ° C, and the air flow rate decreases from atmospheric pressure To -20Pa; the second heating stage: it takes 8 hours. During this period, the heating conditions are met: the ambient temperature rises from 300 °C to 500 °C, and the air flow is maintained at -20Pa; the cooling stage: it takes 8 hours, at During this period, the cooling conditions are met: the ambient temperature drops from 500 ° C to room temperature. The other steps are exactly the same. Get catalyst five.
  • honeycomb low-temperature SCR denitration catalysts prepared in the examples and comparative examples were tested for performance. among them:
  • the unhardened wear rate and the hardened wear rate are tested according to the method in "Technical Specification for Detection of Flue Gas Denitration Catalysts in Thermal Power Plants DLT1286-2013".
  • the test instrument for radial compressive strength and axial compressive strength is a compressive tester, which tests the maximum pressure that a catalyst of 150 * 150 * 150mm size is subjected to before it is destroyed.
  • the measuring instruments for specific surface area, pore volume and average pore diameter are specific surface area measuring instruments.
  • the micro specific surface area and dissolved pore diameter of the substance are calculated by calculating the amount of nitrogen adsorbed at low temperature.
  • the test instrument for the denitration efficiency at a temperature of 160-250 ° C is a denitration catalyst performance detection platform, which simulates the actual project design conditions and detects the catalyst catalyst by a flue gas analyzer.
  • catalyst one and catalyst two The difference between catalyst one and catalyst two is that in the production process of catalyst two, the first drying is divided into three stages, and the calcination heating stage is divided into two stages.
  • the specific surface area of catalyst two is increased by 20%, the compressive strength is increased by more than 35%, and the wear rate is slightly reduced.
  • Catalyst 3 and Catalyst 2 The difference between Catalyst 3 and Catalyst 2 is that during the production of Catalyst 3, more silica sol is added, and the proportion of silica sol to titanium molybdenum powder exceeds 1:20.
  • the three-phase catalyst has a specific surface area reduced by more than 10% compared with catalyst two, the denitration efficiency is reduced from 90.2% to 84.6%, and the wear rate and compressive strength are also reduced to varying degrees.
  • Comparative Example 1 no silica powder and silica sol were added, and in Comparative Example 3, less silica sol was added, and neither could be formed. It can be seen that the ratio of titanium molybdenum powder and silica sol cannot be adjusted arbitrarily, otherwise the product performance will be poor or even unable to form.
  • the difference between catalyst four and catalyst five is that in the calcination stage, the end temperature of the second heating stage is different, the end temperature of catalyst two is 530 °C, the end temperature of catalyst four is 600 °C, and 600 °C match
  • the oxygen flux is -30Pa, and the end temperature of catalyst five is 500 °C.

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Abstract

一种蜂窝式低温SCR脱硝催化剂及其制备方法，包括以下步骤:A、混炼：将重量份数为100-150份钛钼粉、8-20份羧甲基纤维素、5-10份聚氧化乙烯、5-7.5份二氧化硅粉、5-7.5份硅溶胶、7-18份木浆、25-50份玻璃纤维、50-80份去离子水、5-15份偏钒酸铵溶液、10-20份偏钨酸铵溶液、30-55份氨水和10-20份乳酸加入混炼机充分混合；混合后抽出混炼机内水汽，钛钼粉中钼含量≥7％；B、成型；C、干燥；D、煅烧。本制备方法降低了能耗，制得的蜂窝式低温SCR脱硝催化剂在温度160-250℃之间的脱硝效率达到83％以上。

Description

蜂窝式低温SCR脱硝催化剂及其制备方法 技术领域
本发明涉及一种蜂窝式低温SCR脱硝催化剂及其制备方法，属于烟气脱硝技术领域。
背景技术
蜂窝式低温SCR脱硝催化剂的生产中往往需要加入钼元素，以提高催化剂的低温性能，钼元素的添加方式与催化剂的生产工艺有紧密联系。
蜂窝式低温SCR脱硝催化剂的生产主要有两种主要方式：涂覆法和混合挤出法。涂覆法是以经过前处理的蜂窝陶瓷(如堇青石)为基质，在其表面涂覆颗粒状催化剂，然后经干燥焙烧得到催化剂，此类催化剂强度高，耐磨损，但活性组分少。混合挤出法是将制备好的颗粒状催化剂添加合适的添加剂，再经过一系列的成型工艺，得到最终想要的催化剂。混合挤出法可以得到均质蜂窝式低温SCR脱硝催化剂，此类催化剂整体充满活性组分。均质蜂窝式低温SCR脱硝催化剂的机械强度高、活性组分多，而且具有开孔率大的平行通道，易于烟气通过，不易发生催化剂的堵塞。由于均质型的蜂窝式低温SCR脱硝催化剂的性能优异，其应用最为广泛。
虽然均质型蜂窝式低温SCR脱硝催化剂具有优异的性能，但目前钼含量较高的蜂窝式低温SCR脱硝催化剂仍需要采用涂覆法生产，其原因是一旦钼元素的含量较高，采用混合挤出法在湿坯挤出阶段难以成型。
发明内容
针对现有技术存在的上述缺陷，本发明提出了一种新的蜂窝式低温SCR脱硝催化剂及其制备方法。
本发明是采用以下的技术方案实现的：
一种蜂窝式低温SCR脱硝催化剂的制备方法，包括以下步骤:
A、混炼：将重量份数为100-150份钛钼粉、8-20份羧甲基纤维素、5-10份聚氧化乙烯、5-7.5份二氧化硅粉、5-7.5份硅溶胶、7-18份木浆、25-50份玻璃纤维、50-80份去离子水、5-15份偏钒酸铵溶液、10-20份偏钨酸铵溶液、30-55份氨水和10-20份乳酸加入混炼机充分混合；混合后抽出混炼机内水汽；抽湿后得到的物料含水率为25％-30％。所述钛钼粉中钼含量≥7％。
B、成型：混炼得到的物料过滤后放入挤出机，挤出成型，得到湿坯；湿坯的成本开孔 率可达80％以上。
C、干燥：将湿坯放入干燥设备进行干燥，得到干燥后的坯体；
D、煅烧：将干燥后的坯体放入煅烧设备进行煅烧，得到蜂窝式低温SCR脱硝催化剂。
本发明所用的钛钼粉中钼的含量≥7％，在使用混合挤出法制备SCR脱硝催化剂时，一旦钼的含量过高，就难以成型。
本发明以混合的方式加入硅溶胶，可降低粉体混合后的比表面积，从而使混炼后的物料能够顺利挤出成型。钼的含量越高，获得的蜂窝式低温SCR脱硝催化剂的低温性能越好，使用本方法所获得的催化剂具有更优的低温性能。本发明中，钛钼粉和硅溶胶的份数比例应为20:1，不能随意调整，否则成型效果较差，甚至无法成型。
进一步地，所述步骤C包括以下小步：
a)一次干燥：耗时8-11天，在此期间，干燥条件满足：环境温度从30℃上升到70℃，送风频率从15Hz上升到50Hz，空气湿度从80％下降到10％；
b)环境温度自然降温到35℃时，进行二次干燥：耗时14小时，在此期间，干燥条件满足：环境温度从35℃上升到60℃。干燥得到的物料含水率为5％-10％。
进一步地，所述步骤D包括以下小步：
c)升温阶段：耗时14-18小时，在此期间，升温条件满足：环境温度从室温上升到530℃，空气通入量维持在-20Pa；
d)降温阶段：耗时7-9小时，在此期间，降温条件满足：环境温度从530℃下降到室温。
现有技术中以混合挤出法生产蜂窝式低温SCR脱硝催化剂的煅烧温度在600℃以上，一旦煅烧温度低于600℃，所得到的催化剂的机械强度就无法保证，在后续的加工和使用过程中极易碎裂。但煅烧温度越高，能耗就越高，催化剂的比表面积就越低。本发明在混炼阶段加入了硅溶胶，虽然更有助于挤出成型，但粉体混合后的比表面积却更低了。因此，为了得到高脱硝效率的催化剂，需要在后续步骤中设法提高物料的比表面积。
为了抑制催化剂在煅烧时过分烧结，获得更高的催化剂比表面积，本申请降低了空气通入量，将空气通入量从常规的-30Pa提高到-20Pa，吸入的氧气量降低，降低了催化剂在煅烧时的烧结程度，获得更大的比表面积。二氧化硅粉和硅溶胶的加入可以提高催化剂的机械强度，硅的大分子在抑制催化剂烧结的同时保证低温煅烧后的物理性能，不会出现催化剂在使用过程中因物理性能不达标而破碎的问题。此外，在加入二氧化硅粉和硅溶胶之后发现，即使在530℃的温度下煅烧，也可以得到具有合格机械强度的催化剂，降低了能耗。
进一步地，所述小步a)包括以下阶段：
第一阶段：耗时3-4天，在此期间，干燥条件满足：环境温度从30℃上升到40℃，送风频率从15Hz上升到30Hz，空气湿度从80％下降到70％；
第二阶段：耗时3-4天，在此期间，干燥条件满足：环境温度从40℃上升到60℃，送风频率从30Hz上升到40Hz，空气湿度从70％下降到40％；
第三阶段：耗时2-3天，在此期间，干燥条件满足：环境温度从60℃上升到70℃，送风频率从40Hz上升到60Hz，空气湿度从40％下降到10％。
进一步地，所述小步c)包括以下阶段：
第一升温阶段：耗时7-9小时，在此期间，升温条件满足：环境温度从室温上升到300℃，空气通入量从常压降低到-20Pa；
第二升温阶段：耗时7-9小时，在此期间，升温条件满足：环境温度从300℃上升到530℃，空气通入量维持在-20Pa。
进一步地，所述步骤B使用挤出模具进行挤出成型，挤出模具的表面经化学镀镍处理。
化学镀镍增加了模具表面的光洁程度，挤出过程更为顺畅，挤出的湿坯更平整。
进一步地，所述步骤B所使用挤出模具的缝宽可通过调整镀镍层厚度进行调整。若需要更大的缝宽，只需在挤出模具的制备过程中镀上较薄的镍层，若需要更小的缝宽，只需在挤出模具的制备过程中镀上较厚的镍层。
采用本发明所述的方法制得的蜂窝式低温SCR脱硝催化剂。
本发明的有益效果是：
1、采用混合挤出法成功制备出高钼含量的蜂窝式低温SCR脱硝催化剂，解决了高钼含量的物料在湿坯挤出阶段不易成型的问题。
2、降低了煅烧温度，使其在530℃的温度下仍具有合格的机械强度，节省了能耗。
3、低温煅烧和更低的氧气通入量给最终产品带来了更高的比表面积。
4、制得的蜂窝式低温SCR脱硝催化剂在温度160-250℃之间的脱硝效率达到83％以上。
具体实施方式
为了使本发明目的、技术方案更加清楚明白，对本发明作进一步详细说明。
实施例一：
一种蜂窝式低温SCR脱硝催化剂，其制备方法包括以下步骤：
混炼：将100份美国美礼连公司生产的型号SC-X10的钛钼粉(其中钼含量≥7％)、8份羧甲基纤维素、5份聚氧化乙烯、5份二氧化硅粉、5份硅溶胶、7份木浆、25份玻璃纤维、 50份去离子水、5份偏钒酸铵溶液、10份偏钨酸铵溶液、30份氨水和10份乳酸加入混炼机充分混合；混合后抽出混炼机内水汽；所述钛钼粉中钼含量≥7％；
成型：混炼得到的物料过滤后放入挤出机，挤出成型，得到湿坯；本步骤中挤出模具的表面经化学镀镍处理，镍层厚度为单边100μm，挤出模具的挤出口缝宽为0.8mm。
干燥：将湿坯放入干燥设备进行干燥，得到干燥后的坯体；包括以下小步：一次干燥：耗时8天，在此期间，干燥条件满足：环境温度从30℃上升到70℃，送风频率从15Hz上升到50Hz，空气湿度从80％下降到10％；环境温度自然降温到35℃时，进行二次干燥：耗时14小时，在此期间，干燥条件满足：环境温度从35℃上升到60℃。
煅烧：将干燥后的坯体放入煅烧设备进行煅烧，得到蜂窝式低温SCR脱硝催化剂。包括以下小步：升温阶段：耗时14小时，在此期间，升温条件满足：环境温度从室温上升到530℃，空气通入量从常压降低到-20Pa；降温阶段：耗时7小时，在此期间，降温条件满足：环境温度从530℃下降到室温。得到催化剂一。
实施例二：
一种蜂窝式低温SCR脱硝催化剂，其制备方法包括以下步骤：
混炼：将150份美国美礼连公司生产的型号SC-X10的钛钼粉(其中钼含量≥7％)、20份羧甲基纤维素、10份聚氧化乙烯、7.5份二氧化硅粉、7.5份硅溶胶、18份木浆、50份玻璃纤维、80份去离子水、15份偏钒酸铵溶液、20份偏钨酸铵溶液、55份氨水和15份乳酸加入混炼机充分混合；混合后抽出混炼机内水汽；
成型：混炼得到的物料过滤后放入挤出机，挤出成型，得到湿坯；本步骤中挤出模具的表面经化学镀镍处理，镍层厚度为单边100μm，挤出模具的挤出口缝宽为0.8mm。。
干燥：将湿坯放入干燥设备进行干燥，得到干燥后的坯体；包括：一次干燥：第一阶段：耗时4天，在此期间，干燥条件满足：环境温度从30℃上升到40℃，送风频率从15Hz上升到30Hz，空气湿度从80％下降到70％；第二阶段：耗时3天，在此期间，干燥条件满足：环境温度从40℃上升到60℃，送风频率从30Hz上升到40Hz，空气湿度从70％下降到40％；第三阶段：耗时2天，在此期间，干燥条件满足：环境温度从60℃上升到70℃，送风频率从40Hz上升到60Hz，空气湿度从40％下降到10％。环境温度自然降温到35℃时，进行二次干燥：耗时14小时，在此期间，干燥条件满足：环境温度从35℃上升到60℃。
煅烧：将干燥后的坯体放入煅烧设备进行煅烧，得到蜂窝式低温SCR脱硝催化剂。包括：升温阶段，包括以下阶段：第一升温阶段：耗时8小时，在此期间，升温条件满足：环境温度从室温上升到300℃，空气通入量从常压降低到-20Pa；第二升温阶段：耗时8小时，在此 期间，升温条件满足：环境温度从300℃上升到530℃，空气通入量维持在-20Pa；降温阶段：耗时8小时，在此期间，降温条件满足：环境温度从530℃下降到室温。得到催化剂二。
对比例一：
与实施例二的区别在于，混炼阶段未加入二氧化硅粉和硅溶胶，混炼阶段的其他步骤完全相同，无法成型。
对比例二：
与实施例二的区别在于，硅溶胶的添加量为10份，其他步骤完全相同。得到催化剂三。
对比例三：
与实施例二的区别在于，硅溶胶的添加量为3份，混炼阶段的其他步骤完全相同，无法成型。
对比例四：
与实施例二的区别在于，升温阶段，包括以下阶段：第一升温阶段：耗时8小时，在此期间，升温条件满足：环境温度从室温上升到300℃，空气通入量从常压降低到-30Pa；第二升温阶段：耗时8小时，在此期间，升温条件满足：环境温度从300℃上升到600℃，空气通入量维持在-30Pa；降温阶段：耗时8小时，在此期间，降温条件满足：环境温度从600℃下降到室温。其他步骤完全相同。得到催化剂四。
对比例五：
与实施例二的区别在于，升温阶段，包括以下阶段：第一升温阶段：耗时8小时，在此期间，升温条件满足：环境温度从室温上升到300℃，空气通入量从常压降低到-20Pa；第二升温阶段：耗时8小时，在此期间，升温条件满足：环境温度从300℃上升到500℃，空气通入量维持在-20Pa；降温阶段：耗时8小时，在此期间，降温条件满足：环境温度从500℃下降到室温。其他步骤完全相同。得到催化剂五。
性能测试：
将实施例和对比例制得的蜂窝式低温SCR脱硝催化剂进行性能测试。其中：
未硬化磨损率和硬化磨损率按照《火电厂烟气脱硝催化剂检测技术规范DLT1286-2013》中的方法测试，单位质量的催化剂在一定质量的石英砂中损失的质量比。
径向抗压强度和轴向抗压强度的测试仪器为抗压测试仪，测试150*150*150mm尺寸的催化剂在破坏前受到的最大压力。
比表面积、孔容和平均孔径的测试仪器为比表面积测试仪，通过计算低温吸附的氮气量 来计算物质的微观比表面积和溶孔孔径。
在温度160-250℃之间的脱硝效率的测试仪器为脱硝催化剂性能检测平台，模拟实际的项目设计工况，通过烟气分析仪检测催化剂的催化剂。
测试结果如表1所示：
表1催化剂测试结果对比表
  催化剂一 催化剂二 催化剂三 催化剂四 催化剂五
未硬化磨损率(％/kg) 0.107 0.075 0.093 0.062 0.110
硬化磨损率(％/kg) 0.066 0.040 0.061 0.032 0.063
径向抗压强度(MPa) 0.82 1.11 0.92 1.22 0.70
轴向抗压强度(MPa) 2.11 2.91 2.23 2.88 2.04
比表面积(㎡/g) 51 60 53 30 52
孔容(ml/g) 0.26 0.30 0.28 0.21 0.25
平均孔径(nm) 213 180 197 230 217
160-250℃脱硝效率 83.3％ 90.2％ 84.6％ 55.7％ 84.0％
催化剂一和催化剂二的区别在于，催化剂二在生产过程中，将第一次干燥分为三个阶段，将煅烧的升温阶段分为两个阶段。通过催化剂一和催化剂二的参数比较发现，催化剂二的比表面积提升了20％，抗压强度提高了35％以上，磨损率略有下降。
催化剂三与催化剂二的区别在于，催化剂三在生产过程中，加入了更多的硅溶胶，硅溶胶与钛钼粉的份数比例超过1：20。通过催化剂三和催化剂二的参数比较发现，催化剂三相较于催化剂二，比表面积降低了10％以上，脱硝效率从90.2％降低到84.6％，磨损率和抗压强度也有不同程度的降低。对比例一未加入二氧化硅粉和硅溶胶，对比例三加入了较少的硅溶胶，均无法成型。可见，钛钼粉和硅溶胶的比例不能随意调整，否则产品性能差甚至无法成型。
与催化剂二相比，催化剂四和催化剂五的区别在于，煅烧阶段中，第二升温阶段的终点温度不同，催化剂二的终点温度为530℃，催化剂四终点温度为600℃，与600℃相匹配的氧气通入量为-30Pa，催化剂五的终点温度为500℃。通过参数对比可以发现，若终点温度过高，会造成催化剂烧结，使脱硝效率降低到55.7％。若终点温度过低，最终产品的强度差，磨损率高。而530℃既能够保证脱硝效率，又具有足够的机械强度。

Claims (7)

  1. 一种蜂窝式低温SCR脱硝催化剂的制备方法，其特征在于，包括以下步骤:
    A、混炼：将重量份数为100-150份钛钼粉、8-20份羧甲基纤维素、5-10份聚氧化乙烯、5-7.5份二氧化硅粉、5-7.5份硅溶胶、7-18份木浆、25-50份玻璃纤维、50-80份去离子水、5-15份偏钒酸铵溶液、10-20份偏钨酸铵溶液、30-55份氨水和10-20份乳酸加入混炼机充分混合；混合后抽出混炼机内水汽；所述钛钼粉中钼含量≥7％；
    B、成型：混炼得到的物料过滤后放入挤出机，挤出成型，得到湿坯；
    C、干燥：将湿坯放入干燥设备进行干燥，得到干燥后的坯体；
    D、煅烧：将干燥后的坯体放入煅烧设备进行煅烧，得到蜂窝式低温SCR脱硝催化剂。
  2. 根据权利要求1所述的蜂窝式低温SCR脱硝催化剂的制备方法，其特征在于，所述步骤C包括以下小步：
    a)一次干燥：耗时8-11天，在此期间，干燥条件满足：环境温度从30℃上升到70℃，送风频率从15Hz上升到50Hz，空气湿度从80％下降到10％；
    b)环境温度自然降温到35℃时，进行二次干燥：耗时14小时，在此期间，干燥条件满足：环境温度从35℃上升到60℃。
  3. 根据权利要求1所述的蜂窝式低温SCR脱硝催化剂的制备方法，其特征在于，所述步骤D包括以下小步：
    c)升温阶段：耗时14-18小时，在此期间，升温条件满足：环境温度从室温上升到530℃，空气通入量从常压降低到-20Pa；
    d)降温阶段：耗时7-9小时，在此期间，降温条件满足：环境温度从530℃下降到室温。
  4. 根据权利要求2所述的蜂窝式低温SCR脱硝催化剂的制备方法，其特征在于，所述小步a)包括以下阶段：
    第一阶段：耗时3-4天，在此期间，干燥条件满足：环境温度从30℃上升到40℃，送风频率从15Hz上升到30Hz，空气湿度从80％下降到70％；
    第二阶段：耗时3-4天，在此期间，干燥条件满足：环境温度从40℃上升到60℃，送风频率从30Hz上升到40Hz，空气湿度从70％下降到40％；
    第三阶段：耗时2-3天，在此期间，干燥条件满足：环境温度从60℃上升到70℃，送风频率从40Hz上升到60Hz，空气湿度从40％下降到10％。
  5. 根据权利要求3所述的蜂窝式低温SCR脱硝催化剂的制备方法，其特征在于，所述小步c)包括以下阶段：
    第一升温阶段：耗时7-9小时，在此期间，升温条件满足：环境温度从室温上升到300℃， 空气通入量从常压降低到-20Pa；
    第二升温阶段：耗时7-9小时，在此期间，升温条件满足：环境温度从300℃上升到530℃，空气通入量维持在-20Pa。
  6. 根据权利要求1所述的蜂窝式低温SCR脱硝催化剂的制备方法，其特征在于，所述步骤B使用挤出模具进行挤出成型，挤出模具的表面经化学镀镍处理。
  7. 采用权利要求1-6任意一项所述的蜂窝式低温SCR脱硝催化剂的制备方法制得的蜂窝式低温SCR脱硝催化剂。
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