WO2022016592A1 - 一种石油焦制备脱汞活性炭的制备方法 - Google Patents

一种石油焦制备脱汞活性炭的制备方法 Download PDF

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WO2022016592A1
WO2022016592A1 PCT/CN2020/105416 CN2020105416W WO2022016592A1 WO 2022016592 A1 WO2022016592 A1 WO 2022016592A1 CN 2020105416 W CN2020105416 W CN 2020105416W WO 2022016592 A1 WO2022016592 A1 WO 2022016592A1
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activated carbon
petroleum coke
mercury
sulfur
drying
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PCT/CN2020/105416
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English (en)
French (fr)
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史楷岐
吴韬
蓝勇勇
徐少晨
陈艺珮
杨刚
罗象
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宁波诺丁汉新材料研究院有限公司
艾特科奔有限公司
宁波诺丁汉大学
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Publication of WO2022016592A1 publication Critical patent/WO2022016592A1/zh

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    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B32/00—Carbon; Compounds thereof
    • C01B32/30—Active carbon
    • C01B32/312—Preparation
    • C01B32/318—Preparation characterised by the starting materials
    • C01B32/33—Preparation characterised by the starting materials from distillation residues of coal or petroleum; from petroleum acid sludge
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B32/00—Carbon; Compounds thereof
    • C01B32/30—Active carbon
    • C01B32/312—Preparation
    • C01B32/342—Preparation characterised by non-gaseous activating agents
    • C01B32/348—Metallic compounds

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  • the invention relates to the field of fine chemical industry, and mainly relates to a preparation method of petroleum coke to prepare mercury-removing activated carbon.
  • the mercury removal activated carbon product uses petroleum coke as raw material, and is made into sulfur-containing activated carbon through a special process.
  • This product is widely used in natural gas and other waste gas containing mercury, and is especially suitable for the treatment of low-concentration mercury-containing gas that cannot be removed by other methods, making it meet or lower than the national emission standard; it can also develop and produce special indicators according to the actual requirements of users.
  • Activated carbon uses petroleum coke as raw material, and is made into sulfur-containing activated carbon through a special process.
  • petroleum coke is rich in raw materials, high in carbon content, generally 85-95%, and low in ash ( ⁇ 0.5%).
  • the raw material is high, and it is relatively difficult to activate.
  • the broken petroleum coke is directly heated to 500-800 °C for 10-60 mins to obtain activated carbon.
  • the specific surface area of the activated carbon obtained by this method is not high, and the yield is too low;
  • JP74-14395 Activates petroleum with steam at 900 °C Coke, the iodine adsorption value of the prepared activated carbon was 600 mg/g.
  • alkali metal hydroxides such as KOH are activated, and the ratio of alkali to carbon is generally 3 to 8: 1.
  • KOH and KOH in the prior art.
  • the petroleum coke is directly mixed at a mass ratio of 5:1 and then activated at high temperature, and the specific surface area of the product exceeds 3500 m 2 /g.
  • the specific surface area of the activated carbon prepared by this method is high, the ratio of alkali to carbon in the raw material is large, because the price of KOH is very high. , so the product cost is also very high.
  • the present invention aims to provide a preparation method of activated carbon which can not only control the ratio of alkali to carbon, thereby reducing the price of the finished product, but also obtain a larger specific surface area.
  • the present invention provides a method for preparing demercured activated carbon from petroleum coke, the method comprising the following steps:
  • the calcined petroleum coke after the crushing and the alkali metal hydroxide solution are evenly mixed and dried, and the product A is obtained by grinding, and the calcined petroleum coke after the crushing satisfies the condition: it is easy to mix with the alkali metal hydroxide solution Mixed and cannot float on the surface of the alkali metal hydroxide solution;
  • the present invention has the following technical advantages:
  • the preparation method of the present invention has a simple pretreatment process, directly utilizes a crucible for grinding, and has low requirements on equipment;
  • the preparation method of the present invention has a lower dosage of alkaline activator, which can effectively reduce costs
  • the preparation method of the present invention has a short reaction time and utilizes microwave technology, which greatly reduces energy consumption.
  • Fig. 1 is the preparation method flow chart of a preferred embodiment of the present invention
  • Figure 2(a) is the scanning electron microscope image of Canadian petroleum coke at 20 ⁇ m
  • Figure 2(b) is the SEM image of Zhenhai petroleum coke at 20 ⁇ m
  • Figure 3(a) is a scanning electron microscope image of activated carbon prepared from Canadian petroleum coke at 2 ⁇ m;
  • Figure 3(b) is a scanning electron microscope image of activated carbon prepared from Zhenhai petroleum coke at 2 ⁇ m;
  • Fig. 4 is the XRD diffraction pattern of Zhenhai petroleum coke as-is and Zhenhai petroleum coke as-is;
  • Fig. 5 is the XRD diffraction pattern of Zhenhai and Canadian activated carbon samples
  • Figure 6 is the breakthrough curve of activated carbon adsorption and mercury removal at different adsorption temperatures
  • Fig. 7 is the curve of cumulative mercury adsorption per unit mass of activated carbon at different adsorption temperatures
  • Fig. 8 is the breakthrough curve of the adsorption and removal of mercury by activated carbon under different Hg 0 concentrations
  • Fig. 9 is the curve of cumulative mercury adsorption per unit mass of activated carbon under different Hg 0 concentrations
  • Figure 10 is the breakthrough curve of activated carbon in the adsorption and removal of mercury in nitrogen and nitrogen sulfur dioxide mixture
  • Figure 11 is the cumulative mercury adsorption curve per unit mass of activated carbon in a mixture of nitrogen and nitrogen sulfur dioxide.
  • the invention uses petroleum coke as raw material to prepare activated carbon by chemical activation method and activation reagent.
  • activating reagents There are many types of activating reagents, the common ones include: KOH, NaOH, ZnCl 2 and so on.
  • KOH was more effective in producing microporous activated carbon.
  • Another advantage of using KOH is its environmentally friendly characteristics, using ZnCl 2 to the production of mesoporous activated carbon is more effective, but Zn is a metal harmful to the environment. In addition to this, it also helps to form cross-linked structures in activated carbon to create highly porous media.
  • the main reactions associated with the chemical activation of KOH as an activator are as follows:
  • Carbonization refers to the endothermic decomposition of carbon precursors. More specifically, in the carbonization stage, the carbon material is produced by heating the carbon precursor in the absence of oxygen to decompose the non-carbonaceous species. Usually the carbonization stage is carried out in an inert atmosphere of nitrogen using a stationary or rotating fluidized bed furnace. In the carbonization stage, factors such as heating temperature, heating rate, heating time and surrounding environment have an impact on the coke produced. Among these factors, temperature plays a crucial role.
  • a heating rate that is too low results in less volatilization and shrinkage of non-carbonaceous materials, which can affect the formation of micropores; a heating rate that is too high results in damage to the micropores and enlargement of mesopores and continuous macropores. It should be emphasized that carbonization at higher extreme temperatures may also lead to the formation of graphite rather than coke.
  • the present invention provides a kind of preparation method of petroleum coke to prepare demercured activated carbon, and described method comprises the following steps:
  • the calcined petroleum coke after the crushing and the alkali metal hydroxide solution are evenly mixed and dried, and the product A is obtained by grinding, and the calcined petroleum coke after the crushing satisfies the condition: it is easy to mix with the alkali metal hydroxide solution Mixed and cannot float on the surface of the alkali metal hydroxide solution;
  • the preparation method of the present invention has a simple pretreatment process, directly uses a crucible for grinding, and has low requirements on equipment;
  • the preparation method of the present invention has a lower dosage of the alkaline activator, which can effectively reduce the cost
  • the preparation method of the present invention has a short reaction time and utilizes microwave technology, which greatly reduces energy consumption.
  • step S100 the calcined petroleum coke is crushed to 50-200 mesh.
  • the mesh number is small, the mixing effect with the alkali metal solution is not ideal; when the mesh number is too large, the petroleum coke powder is too fine to sink, and the mixing effect of a large amount of floating on the surface of the solution is not ideal.
  • the alkali metal hydroxide solution in step S200 is KOH or NaOH solution, or a mixed solution of the two.
  • the mixing temperature in step S200 is 110° C.
  • the mixing time is 8-48 h.
  • step S200 the drying time is 1-5h, the drying temperature is 80-120°C, the grinding time is 1-3h, and the grinding time is 100-200 mesh.
  • ensuring the retention of sulfur element in step S300 is achieved by controlling the time and temperature of the microwave activation reaction.
  • the reaction temperature in step S300 is 600-800° C., and the reaction time is 10-60 mins.
  • the drying temperature in step S300 is 80-120° C., and the drying time is 1-5 h.
  • the alkali metal hydroxide solution is KOH or NaOH solution
  • the drying temperature is 90°C
  • the drying time is 48h
  • the drying time is 2.5h
  • the drying temperature is 80°C
  • the grinding time is 1.5h , grind to 100 mesh.
  • the reaction temperature was 600°C
  • the reaction time was 30mins
  • the drying temperature was 80°C
  • the drying time was 5h.
  • the alkali metal hydroxide solution is KOH or NaOH solution
  • the drying temperature is 110°C
  • the drying time is 36h
  • the drying time is 2h
  • the drying temperature is 90°C
  • the grinding time is 2h
  • the grinding time is 150°C. eye.
  • the microwave activation reaction temperature was 700°C
  • the reaction time was 20mins
  • the drying temperature was 90°C
  • the drying time was 2.5h.
  • the alkali metal hydroxide solution is KOH or NaOH solution
  • the drying temperature is 120°C
  • the drying time is 24h
  • the drying time is 1.5h
  • the drying temperature is 100°C
  • the grinding time is 2.5h , grind to 200 mesh.
  • the microwave activation reaction temperature is 800° C.
  • the reaction time is 10 mins
  • the drying temperature is 100° C.
  • the drying time is 1 h.
  • Fig. 2(a) is the scanning electron microscope image of Canadian petroleum coke at 20 ⁇ m
  • Fig. 2(b) is the scanning electron microscope image of Zhenhai petroleum coke at 20 ⁇ m. From the morphological point of view, there is little difference between the two raw materials
  • Fig. 3(a) is the SEM image of activated carbon prepared from Canadian petroleum coke at 2 ⁇ m
  • 3(b) is the SEM image of activated carbon prepared from Zhenhai petroleum coke at 2 ⁇ m, from Fig. 3(a) ) and Figure 3(b), the microscopic morphology of the activated carbon prepared from Canadian petroleum coke and the activated carbon prepared from Zhenhai petroleum coke is not much different.
  • the main component of the two raw materials is C, and the other elements are a small amount of nitrogen, oxygen, sulfur, and potassium.
  • Canadian petroleum coke also contains a small amount of silicon and aluminum. .
  • Figure 5 shows the XRD diffraction patterns of Zhenhai and Canadian activated carbon samples. From these figures, it can be seen that the peak width of the characteristic peaks of activated carbon is broadened and the intensity is also significantly decreased, indicating that the structural disorder of the samples after KOH activation is intensified.
  • the crystallite structure parameters d 002 , L c and L a of the samples were obtained by spectral calculation.
  • the pore walls of activated carbon are composed of graphite crystallites, and the reduction of the crystallite size can lead to the widening of the pores. Can be obtained by calculation, the graphite crystallites small thickness Lo after activation, L a slightly decreases; d 002 value and is increased after activation.
  • a sulfur atom itself has at least one lone electron pair interact with the Hg 0 form covalent bonds, or as an initial attachment point in order to achieve oxidation and removal of Hg 0. Therefore, the adsorption of sulfur and mercury can be classified into three steps: mercury oxidation, electron transfer, and electron rearrangement. First, the C atom is connected with the S atom in the form of a single bond.
  • the simulation method of the present invention mercury adsorption experiments were carried out under an atmosphere of N 2, N 2 flow rate of the mercury contained 200mL / min, the total flow rate of simulated flue gas 2L / min of activated carbon addition amount of 25mg, particle diameter 30.8 ⁇ m-150 ⁇ m, adsorption
  • the inlet Hg 0 concentration was 35 ⁇ g/m 3 .
  • Figures 6 and 7 show the breakthrough curve and the cumulative mercury adsorption per unit mass curve of activated carbon for adsorption and removal of mercury at different adsorption temperatures. It is found that the mercury removal effect is the worst at 25 °C, and the mercury removal effect is the best at 75 °C. Between 75 °C and 125 °C, the higher the adsorption temperature, the higher the Hg0 penetration rate, and the lower the mercury removal efficiency.
  • the cumulative mercury adsorption per unit mass at 75°C was 201.7 ug/g, which were 2.71, 1.59, 1.05 and 1.98 times the mercury adsorption at 25°C, 50°C, 100°C and 125°C, respectively.
  • the sulfur-loaded activated carbon has both physical adsorption and chemical adsorption in the process of mercury removal.
  • the mercury removal agent mainly occurs physical adsorption, and the adsorption capacity is weak.
  • chemical adsorption was the main method, and the mercury removal efficiency was significantly improved.
  • the decrease of physical adsorption and the reverse shift of chemical equilibrium resulted in the increase of penetration rate.
  • the sulfur melts into a liquid state, thereby weakening the chemical bond between sulfur and mercury, and there is a problem of precipitation of elemental sulfur, which is not conducive to the diffusion of gaseous mercury.
  • the mercury content in my country's raw coal varies from 0.1 to 5.5 mg/Kg, with an average mercury content of 0.22 mg/Kg. Due to the huge annual consumption of coal burning in my country, the amount of mercury and its pollutants emitted from coal burning every year is very alarming, and the growth rate is fast, posing a huge threat to human health and the ecological environment. Therefore, the control of coal burning flue gas Mercury emissions are of great significance. When coal is burned, most of the mercury is discharged into the atmosphere with the flue gas, and only a small part enters the ash. Among them, the fly ash accounts for 23.1%-26.9%, and the flue gas accounts for 56.3%-69.7%. 2% or so.
  • the key to controlling mercury pollution from coal combustion is to control the emission of mercury in flue gas into the atmosphere.
  • the mercury content in coal-fired flue gas is 9-23 ⁇ g/m3, which is a trace-level pollutant, and there are three main forms: gaseous elemental mercury, gaseous oxidized mercury, and solid particulate mercury.
  • gaseous elemental mercury is the main form of mercury in flue gas.
  • the existence form of mercury in flue gas has an important influence on the removal of mercury.
  • N 2 flow rate of the mercury contained 200mL / min, the total flow rate of simulated flue gas 2L / min of activated carbon addition amount of 25mg, particle diameter 30.8 ⁇ m-150 ⁇ m, the adsorption temperature of 70 °C.
  • Figures 8 and 9 are the breakthrough curve and the cumulative mercury adsorption per unit mass curve of activated carbon under different Hg 0 concentrations, respectively.
  • the Hg 0 concentrations in the flue gas are 15, 25, 35 and 45 ⁇ g/m 3 , respectively .
  • the higher the Hg 0 concentration in the flue gas the lower the mercury removal rate of activated carbon, and the mercury removal effect is also inhibited. It may be due to the small amount of activated carbon, when the Hg° concentration is too high and the residence time is small, the Hg 0 in the atmosphere quickly passes through the adsorption layer before the adsorption reaction with the sulfur-loaded activated carbon occurs.
  • Hg 0 concentration increases the initial rate of adsorption of the mercury sorbent, since the Hg 0 concentration is increased to enhance the driving force Hg 0 molecules diffuse to the surface of the adsorbent the micropores, resulting in the adsorption equilibrium reaction forward movement .
  • Figures 10 and 11 are the breakthrough curve and the cumulative mercury adsorption per unit mass curve of activated carbon in the adsorption and removal of mercury in a mixture of nitrogen and nitrogen sulfur dioxide, respectively. It may be the presence of SO 2 inhibits the removal of mercury.
  • the adsorption energy of SO 2 on the adsorbent surface is stronger than that of Hg 0 , and the bonding between sulfur and carbon is stronger than that between sulfur and mercury.
  • SO 2 molecules will bind to the oxygen containing functional groups of the surface of the adsorbent, the adsorbent occupies size and surface active sites, a competitive adsorption, thereby inhibiting removal of Hg 0.
  • the optimal reaction temperature range is 500-800°C, especially preferably, the reaction temperature range is controlled at 600-700°C, Further, considering the peak value of Hg adsorption in the above table, the reaction temperature is preferably 600°C or about 600°C, the left and right range can be plus or minus 50°C, and the limit of the left and right range is plus or minus 100°C.

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Abstract

提供一种石油焦制备脱汞活性炭的方法，涉及环境化工领域，包括步骤：S100、将煅前石油焦破碎；S200、将所述煅前石油焦与碱金属氢氧化物溶液混合均匀，烘干，研磨得到产物A；S300、在惰性气氛保护下将所述A进行活化反应并确保反应过程中有硫元素依然存留在其中，冷却后经洗涤、干燥得到活性炭产品。该制备方法应用微波加热技术，反应时间短能耗低，且微波强化了活化反应，所得活性炭比空隙丰富、比面积大，石油焦经微波加热活化制备的活性炭含有一定含量的硫，特别适用于脱汞应用。

Description

一种石油焦制备脱汞活性炭的制备方法 技术领域
本发明涉及精细化工领域，主要涉及一种石油焦制备脱汞活性炭的制备方法。
背景技术
脱汞活性炭产品采用石油焦为原材料，经特殊工艺制成含硫活性炭。本产品广泛适用于天然气及其它含有汞的废气，还特别适用于其它方法不能除去的低浓度含汞气体处理，使其达到或低于国家排放标准；也可按用户实际要求，研制生产特殊指标活性炭。
石油焦作为石油化工的副产品，原料丰富，含碳量高，一般在85～95％，且灰份低(＜0.5％)，是制备活性炭的理想原料，但石油焦石墨化程度较其他几类原料要高，相对比较难于活化。现有技术直接将破碎的石油焦升温至500～800℃保持10～60mins得到活性炭，该方法制得的活性炭比表面积不高，收率太低；JP74-14395在900℃下以水蒸汽活化石油焦，制得活性炭的碘吸附值为600mg/g。也有关于以石油焦为原料采用化学活化法制备活性炭的报道，其中以KOH等碱金属氢氧化物活化为主，碱与炭的比例一般在3～8∶1，现有技术中有将KOH与石油焦按5∶1的质量比直接混合后高温活化，产品比表面积超过3500m 2/g，该方法制备的活性炭比表面积虽高，但是原料中碱与炭的比例大，由于KOH的价格很高，所以导致产品成本也非常高。
因此，本领域技术人员致力于开发一种既可以控制碱与炭的比例，从而降低成品价格，又可以获得较大的比表面积的活性炭的制备方法。
发明内容
有鉴于现有技术的上述缺陷，本发明致力于提供一种既可以控制碱与炭的比例，从而降低成品价格，又可以获得较大的比表面积的活性炭的制备方法。
为实现上述目的，本发明提供了一种石油焦制备脱汞活性炭的方法，所述方法包括以下步骤：
S100、将煅前石油焦破碎；
S200、将所述破碎后的煅前石油焦与碱金属氢氧化物溶液混合均匀后烘干，研磨得到产物A，破碎后的煅前石油焦满足条件：易于与所述碱金属氢氧化物溶液混合且不能浮在所述碱金属氢氧化物溶液上表面；
S300、在惰性气氛保护下将所述产物A进行微波活化反应并确保反应过程中有硫元素依然存留在其中，冷却后经洗涤、干燥得到活性炭产品。
本发明与现有技术相比，具有以下技术优势：
(1)本发明的制备方法预处理工艺简单，直接利用坩埚进行研磨，对设备要求低；
(2)本发明的制备方法碱性活化剂用量较低，可以有效降低成本；
(3)本发明的制备方法反应时间短并且利用微波技术，大大降低了能耗。
附图说明
图1是本发明的一个较佳实施例的制备方法流程图；
图2(a)为加拿大石油焦在20μm下的扫描电镜图；
图2(b)为镇海石油焦在20μm下的扫描电镜图；
图3(a)为以加拿大石油焦为原料制备的活性炭在2μm下的扫描电镜图；
图3(b)为以镇海石油焦为原料制备的活性炭在2μm下的扫描电镜图；
图4为镇海石油焦原样和镇海石油焦原样的XRD衍射图谱；
图5为镇海和加拿大活性炭样品的XRD衍射图谱；
图6为活性炭在不同吸附温度下吸附脱汞的穿透曲线；
图7为活性炭在不同吸附温度下单位质量累积汞吸附量曲线；
图8为活性炭在不同Hg 0浓度下吸附脱汞的穿透曲线；
图9为活性炭在不同Hg 0浓度下单位质量累积汞吸附量曲线；
图10为活性炭在氮气和氮气二氧化硫混合气吸附脱汞的穿透曲线；
图11为活性炭在氮气和氮气二氧化硫混合气单位质量累积汞吸附量曲线。
具体实施方式
本发明是以石油焦为原料通过化学活化法使用活化试剂制备得到活性炭的方法。活化试剂的种类较多，常见的包括：KOH，NaOH，ZnCl 2等。在不同的活化剂中，KOH在生产微孔活性炭方面更有效。使用KOH的另一个优势是其环保的特性，使用ZnCl 2来生产中孔活性炭方面更有效，但Zn是一种对环境有害的金属。除此之外，它还有助于形成活性炭中的交联结构以产生高度多孔的介质。与KOH作为活化剂的化学活化相关的主要反应如下：
2KOH→K 2O+H 2O(高温)
C+H 2O→CO+H 2(高温)
CO+H 2O→CO 2+H 2(高温)
K 2O+CO 2→K 2CO 3(高温)
K 2O+H 2→2K+H 2O(高温)
K 2O+CO→2K+CO 2(高温)
一般来说，活性炭制剂经历两个后续阶段：炭化和活化。炭化是指对将碳前体进行吸热分解。更具体地，在炭化阶段，在不存在氧的情况下将炭前驱体加热以分解非碳质物质来生产炭材料。通常炭化阶段是在惰性气氛氮气中，通过使用静止或旋转的流化床炉进行的。在炭化阶段，加热温度，加热速率，加热时间和周围环境等因素对生产的焦炭产生影响。在这些因素中，温度起着至关重要的作用。加热速率过低导致非碳质物质的挥发和收缩较少，这会影响微孔的形成；加热速率过高导致微孔损坏，中孔和连续的大孔扩大。需要强调的，在较高极限温度下的炭化也有可能导致形成石墨而不是焦碳。
如图1所示，本发明提供了一种石油焦制备脱汞活性炭的制备方法，所述方法包括以下步骤：
S100、将煅前石油焦破碎；
S200、将所述破碎后的煅前石油焦与碱金属氢氧化物溶液混合均匀后烘干，研磨得到产物A，破碎后的煅前石油焦满足条件：易于与所述碱金属氢氧化物溶液混合且不能浮在所述碱金属氢氧化物溶液上表面；
S300、在惰性气氛保护下将所述产物A进行微波活化反应并确保所述微波活化反应过程中反应温度兼顾活性炭产品的比表面积和活性炭产品硫元素的平衡，冷却后经洗涤、干燥得到活性炭产品。
一方面，本发明的制备方法预处理工艺简单，直接利用坩埚进行研磨，对设备要求低；
另一方面，本发明的制备方法碱性活化剂用量较低，可以有效降低成本；
最后，本发明的制备方法反应时间短并且利用微波技术，大大降低了能耗。
在一个较佳的实施例中，步骤S100中是将所述将煅前石油焦破碎至50-200目。目数较小时，与碱金属溶液混合效果不理想；目数过大时，石油焦粉末太细，导致无法下沉，大量漂浮在溶液表面混合效果也不理想。
在一个较佳的实施例中，步骤S200中所述碱金属氢氧化物溶液为KOH或NaOH溶液，或二者的混合溶液。
在一个较佳的实施例中，步骤S200中所述混合温度为110℃，混合时间为8-48h。
在一个较佳的实施例中，步骤S200中所述烘干时间为1-5h，烘干温度为80-120℃，所述研磨时间为1-3h，研磨至100-200目。
在一个较佳的实施例中，步骤S300中确保硫元素存留是通过控制微波活化反应的时间和温度实现。
在一个较佳的实施例中，步骤S300中所述反应温度为600-800℃，反应时间为10-60mins。
在一个较佳的实施例中，步骤S300中所述干燥温度为80-120℃，干燥时间为1-5h。
以下参考说明书附图介绍本发明的多个优选实施例，使其技术内容更加清楚和便于理解。本发明可以通过许多不同形式的实施例来得以体现，本发明的保护范围并非仅限于文中提到的实施例。
实施例1
S100、将煅前石油焦破碎至100目；
S200、将所述煅前石油焦与碱金属氢氧化物溶液混合均匀后烘干，研磨得到产物A；
其中，碱金属氢氧化物溶液为KOH或NaOH溶液，烘干温度为90℃，烘干时间为48h，所述烘干时间为2.5h，烘干温度为80℃，所述研磨时间为1.5h，研磨至100目。
S300、在惰性气氛保护下将所述A进行微波活化反应并确保所述微波活化反应过程中反应温度兼顾活性炭产品的比表面积和活性炭产品硫元素的平衡，冷却后经洗涤、干燥得到活性炭产品。
其中，反应温度为600℃，反应时间为30mins，干燥温度为80℃，干燥时间为5h。
实施例2
S100、将煅前石油焦破碎至150目；
S200、将所述煅前石油焦与碱金属氢氧化物溶液混合均匀后烘干，研磨得到产物A；
其中，碱金属氢氧化物溶液为KOH或NaOH溶液，烘干温度为110℃，烘干时间为36h，烘干时间为2h，烘干温度为90℃，所述研磨时间为2h，研磨至150目。
S300、在惰性气氛保护下将所述A进行微波活化反应并确保所述微波活化反应过程中反应温度兼顾活性炭产品的比表面积和活性炭产品硫元素的平衡，冷却后经洗涤、干燥得到活性炭产品。
其中，微波活化反应温度为700℃，反应时间为20mins，干燥温度为90℃，干燥时间为2.5h。
实施例3
S100、将煅前石油焦破碎至200目；
S200、将所述煅前石油焦与碱金属氢氧化物溶液混合均匀后烘干，研磨得到产物A；
其中，碱金属氢氧化物溶液为KOH或NaOH溶液，烘干温度为120℃，烘干时间为24h，所述烘干时间为1.5h，烘干温度为100℃，所述研磨时间为2.5h，研磨至200目。
S300、在惰性气氛保护下将所述A进行微波活化反应并确保所述微波活化反应过程中反应温度兼顾活性炭产品的比表面积和活性炭产品硫元素的平衡，冷却后经洗涤、干燥得到活性炭产品。
其中，所述微波活化反应温度为800℃，反应时间为10mins，干燥温度为100℃，干燥时间为1h。
本发明在实验过程中采用了2种石油焦作为原料，分别是加拿大石油焦和宁波镇海炼化的石油焦。原料分析结果如下：
表1 两种石油焦原料成分分析
Figure PCTCN2020105416-appb-000001
从上图中可以看到，加拿大石油焦在水分(Moisture)、无定形物(Volatile)和硫元素(Sulfur)高于镇海石油焦，固定碳和灰粉稍低于镇海石油焦。图2(a)为加拿大石油焦在20μm下的扫描电镜图，图2(b)为镇海石油焦在20μm下的扫描电镜图，从形貌上看，这两种原料的区别不大；图3(a)为以加拿大石油焦为原料制备的活性炭在2μm下的扫描电镜图；图3(b)为以镇海石油焦为原料制备的活性炭在2μm下的扫描电镜图，从图3(a)和图3(b)看，加拿大石油焦为原料制备的活性炭和以镇海石油焦为原料制备的活性炭的微观形貌区别也不大。
表2 EDS测量两种原料元素成分
Figure PCTCN2020105416-appb-000002
从表2 EDS测量两种原料元素成分分析来看，两种原料的主要成分都为C，其他元素成分就是少量的氮、氧、硫、钾，其中，加拿大石油焦还含有少量的硅和铝。
表3 活性炭产品(2∶1)BET与碘值
Figure PCTCN2020105416-appb-000003
由上表看到，用加拿大石油焦原料制备得到的活性炭的比表面积(BET)要远远高于镇海石油焦原料得到的活性炭的比表面积，但是其碘值稍低于镇海石油焦原料得到的活性炭。
表4 活性炭产品(2∶1)EDS元素测试
Figure PCTCN2020105416-appb-000004
从表4的EDS元素分析结果看，硫元素大部分在加热中流失，另外，在实验进行过程前几分钟(温度没开始陡升时)有黄色含硫烟气生成，硫元素可能在前期中变为气体，但是依然含有硫。
图4所示的是镇海石油焦原样和镇海石油焦原样的XRD衍射图谱。从这些图中可以看出，每个谱图上都有两个特征峰，一个强度较大在2θ＝25°左右，另一个强度很小在43°左右，它们分别是炭材料的(002)和(100)晶面的衍射特征峰。
图5所示为镇海和加拿大活性炭样品的XRD衍射图谱。从这些图可以看出，活性炭的特征峰峰宽变宽，强度也显著下降，说明KOH活化后的样品结构混乱程度加剧。通过谱图计算得到样品的微晶结构参数d 002、L c和L a。活性炭孔道壁 由石墨微晶所组成，微晶尺度的减小可导致孔道的拓宽。通过计算可以得出，石墨微晶厚度Lo在活化之后变小，L a也略有减小；而d 002值则在活化之后增大了。这说明活化后炭微晶尺度变小，导致内部结构的无序化，从而形成较大的比表面积：在活化过程中活化剂与芳环碳层发生反应，生成的钾及其化合物插层或结合进入芳环碳层并扩大了层间距，这使活性炭的石墨微晶结构进一步无序化。
申请人还在碱金属氢氧化物与锻前石油焦的质量比为2∶1，温度分别在500℃、600℃、700℃、800℃、900℃、1000℃时进行实验，在微波活化和马弗炉直接活化下对加拿大活性炭比表面积(BET)和硫含量比进行对比实验结果如下表5所示：
表5 在不同温度得到的活性炭的比表面积和硫含量对比
Figure PCTCN2020105416-appb-000005
从表5在不同温度得到的活性炭的比表面积(BET)和硫含量对比可以得出，随着温度的升高，活性炭的比表面积(BET)也越来越大，但是硫含量越来越低。为了使活性炭既具有较高的比表面积(BET)又不行影响它的脱汞性能，所以最佳的反应温度范围在600-800℃之间。
申请人还分别在碱金属氢氧化物与锻前石油焦的质量比为2∶1，3∶1，4∶1时进行实验，在微波活化和马弗炉直接活化下对加拿大活性炭和镇海活性炭的比表面积(BET)比进行对比实验结果如下表6所示：
表6 在不同碱炭比和处理条件下得到的活性炭的比表面积对比
Figure PCTCN2020105416-appb-000006
从上表6在不同碱炭比和处理条件下得到的活性炭的比表面积对比图中，看 到加拿大石油焦和镇海石油焦在微波处理下的比表面积要大于在同样的碱炭比条件下通过马弗炉处理得到的活性炭的比表面积；同时从表中也可以看到，采用微波技术处理最终得到的活性炭的比表面积大于通过马弗炉处理得到的活性炭的比表面积，同时也可以降低碱的用量，从而使得生产成本降低。
活性炭吸附脱汞实验
硫原子本身至少有一对孤电子与Hg 0相互作用形成共价键，或者作为初始附着点以实现对Hg 0的氧化和脱除。因此，硫与汞的吸附可归为三个步骤：汞的氧化、电子转移、电子重排。首先，C原子与S原子以单键的形式连接，Hg 0被氧化成Hg 2+后与S原子共用两对电子，形成Hg＝S双键；然后，Hg＝S双键中的一个电子逃离转移至C-S单键上：各拥有一个活性电子的Hg原子与C原子以C-Hg单键的形式相互结合，而最初连接C原子与S原子的单键断裂并产生一对孤电子。基于该反应机理，硫酸盐等氧化态硫价态较高，所有电子对均被占满，因此对Hg 0的脱除效果较差：元素硫及其他形态的非氧化态硫本身具有未配对的孤对电子，可以与Hg 0结合进而将其脱除。
本发明方法所模拟汞吸附实验是在N 2气氛下进行的，载汞N 2流量为200mL/min，模拟烟气总流量2L/min活性炭添加量为25mg，粒径为30.8μm-150μm，吸附入口Hg 0浓度为35μg/m 3。
图6和图7分别为活性炭在不同吸附温度下吸附脱汞的穿透曲线和单位质量累积汞吸附量曲线，吸附温度分别为25℃、50℃、75℃、100℃、125℃，可以看出，在25℃时脱汞效果最差，75℃时脱汞效果最好，在75℃到125℃之间，吸附温度越高，Hg0穿透率越高，脱汞效率越低。75℃时的单位质量累积汞吸附量为201.7ug/g，分别为25℃、50℃、100℃和125℃时的汞吸附量的2.71倍、1.59倍、1.05倍和1.98倍。分析原因发现，载硫活性炭在脱汞过程中既存在物理吸附又存在化学吸附。室温下脱汞剂主要发生物理吸附，吸附能力较弱。当吸附温度升高到70℃则以化学吸附为主，脱汞效率明显提高。但随着温度的进一步升高，物理吸附量的降低和化学平衡的逆向移动造成穿透率的增加。另外，当温度高于硫的熔点后，硫熔化变成液态进而减弱硫与汞之间的化学键，并存在单 质硫的析出问题，不利于气态汞的扩散。
我国原煤中汞含量变化范围在0.1-5.5mg/Kg，平均汞含量0.22mg/Kg。由于我国燃煤的年耗量巨大，每年燃煤排放汞及其污染物的量都是非常惊人的，而且增长速度较快，对人类健康和生态环境构成了巨大威胁，因此控制燃煤烟气中汞的排放量具有重要意义。煤燃烧时汞大部分随烟气排入大气，进入灰渣的只占小部分，其中飞灰中占23.1％-26.9％，烟气中占56.3％-69.7％，进入灰渣的汞只占2％左右。因此控制燃煤汞污染关键是控制烟气中的汞向大气中排放。燃煤烟气中汞含量为9-23μg/m3，属于痕量级污染物，其中主要有三种形态：气态单质汞，气态氧化汞，固态颗粒汞。其中气态单质汞是烟气中汞的主要存在形式。烟气中汞的存在形态对汞的脱除有重要影响。
模拟汞吸附实验是在N 2气氛下进行的，载汞N 2流量为200mL/min，模拟烟气总流量2L/min活性炭添加量为25mg，粒径为30.8μm-150μm，吸附温度70℃。
图8和图9分别为活性炭在不同Hg 0浓度下吸附脱汞的穿透曲线和单位质量累积汞吸附量曲线，烟气中Hg 0浓度分别为15、25、35和45μg/m 3。在吸附初始阶段，烟气中Hg 0浓度越高，活性炭对汞的脱除率越低，并且汞脱除效果也受到抑制。可能是由于活性炭用量少当Hg°浓度过高且停留时间较小时，气氛中的Hg 0还未与载硫活性炭进行吸附反应就快速穿过吸附层。此外，Hg 0浓度的增加提高了吸附剂的初始汞吸附速率，这是因为Hg 0浓度的升高增强了Hg 0分子扩散到吸附剂表面微孔中的驱动力，致使吸附反应平衡正向移动。
图10和图11分别为活性炭在氮气和氮气二氧化硫混合气吸附脱汞的穿透曲线和单位质量累积汞吸附量曲线。可能是SO 2的存在会抑制汞的脱除。SO 2在吸附剂表面的吸附能比Hg 0，硫与碳的成键要强于硫与汞。此外，SO 2分子会与吸附剂表面的含氧官能团结合，占据吸附剂的微孔及表面活性位点，形成竞争吸附，进而抑制Hg 0的脱除。
以下表7是在不同温度得到的活性炭的比表面积、硫含量和汞吸附量的对比
表7 在不同温度得到的活性炭的比表面积、硫含量和汞吸附量的对比
Figure PCTCN2020105416-appb-000007
从表7在不同温度下得到的活性炭的比表面积(BET)、硫含量及Hg吸附量对比可以得出如下结论：反应温度越低，活性炭中硫的损失越少，反应时间越短，活性炭中硫的损失越少，因此，可以通过控制活化反应的时间和温度来确保反应过程中硫元素的存留。同时，由上表也可以看到，在温度低于500℃时，硫含量损失较小，但是石油焦反应不充分导致活性炭BET较低，对Hg吸附量减少；在温度高于500℃时，随着温度升高至800℃，BET升高，硫含量降低，但是Hg吸附量减少并不多。所以，为了使得到的活性炭既具有较高的比表面积又不影响它的脱汞性能，所以最佳的反应温度范围在500-800℃，特别优选的，反应温度范围控制在600-700℃，进一步的，按上表Hg吸附量的峰值考虑，反应温度优选600℃或者600℃左右，所述左右幅度可以是正负50℃，左右幅度的极限是正负100℃。
应当说明的是，上述实施例仅为本发明的优选实施方式，并不用于限定本发明，依照实施例所记载的技术方案进行的修改，以及对其中部分技术特征进行等同替换、改进等，均应包含在本发明的保护范围之内。

Claims (9)

  1. 一种石油焦制备脱汞活性炭的制备方法，所述方法包括以下步骤：
    S100、将煅前石油焦破碎；
    S200、将所述破碎后的煅前石油焦与碱金属氢氧化物溶液混合均匀后烘干，研磨得到产物A，破碎后的煅前石油焦满足条件：易于与所述碱金属氢氧化物溶液混合且不能浮在所述碱金属氢氧化物溶液上表面；
    S300、在惰性气氛保护下将所述产物A进行微波活化反应并确保反应过程中有硫元素依然存留在其中，冷却后经洗涤、干燥得到活性炭产品。
  2. 如权利要求1所述的方法，其中，步骤S100中是将所述将煅前石油焦破碎至50-200目。
  3. 如权利要求1所述的方法，其中，步骤S200中所述碱金属氢氧化物溶液为KOH或NaOH溶液，或二者的混合溶液。
  4. 如权利要求1所述的方法，其中，步骤S200中所述煅前石油焦与碱金属氢氧化物溶液混合时间为8-48h。
  5. 如权利要求1所述的方法，其中，步骤S200中所述烘干时间为1-5h，烘干温度为80-120℃，所述研磨时间为1-3h，研磨至100-200目。
  6. 如权利要求1所述的方法，其中，步骤S300中所述微波活化反应温度为600-800℃，反应时间为10-60mins。
  7. 如权利要求1所述的方法，其中，步骤S300中确保硫元素存留是通过控制微波活化反应的时间和温度实现。
  8. 如权利要求1所述的方法，其中，步骤S300中所述干燥温度为80-120℃，干燥时间为1-5h。
  9. 权利要求1～7任意一项权利要求的制备方法制备的含硫活性炭在脱汞方面的应用。
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