基于酸碱作用的油品脱硫和苯酚提取
发布时间：2018-09-11 16:05
【摘要】：油品主要源自石油炼制和煤炭加工而来的产品,包括汽油、柴油、煤焦油、其他煤液体等,是重要的能量与化学品来源。在石油基的燃料油中,含有大量的噻吩硫(S)化物,这些油品的大量使用造成了日益严重的环境问题,如各地频发的雾霾天气和严重的PM2.5污染,以及酸雨等,因此燃油脱硫技术至关重要。同时,对源自煤炭的煤焦油而言,其中含有大量有价值的化学品,是重要的有机化工原料,其中,酚类化合物的提取具有巨大的商业价值和应用前景。对于燃油脱硫而言,传统的加氢脱硫技术(HDS, hydrodesulfurization)反应条件苛刻、辛烷值损失大、处理低硫油品效果差,难以满足越来越严格的硫含量标准。因此,许多非加氢脱硫技术(non-HDS)应运而生,例如吸附脱硫(ADS, adsorptive desulfurization)、萃取脱硫(EDS, extractive desulfurization)、氧化脱硫(ODS, oxidative desulfurization)等。本论文基于Lewis酸碱作用,研究了ADS、EDS、ODS这三种技术对模型油或真实油品的脱硫情况。首先,论文研究了四种Lewis酸AlCl3、FeCl3、ZnCl2以及CuCl对3-甲基噻吩(3-MT,3-methylthiophene)、苯并噻吩(BT, benzothiophene)和二苯并噻吩(DBT,dibenzothiophene)等Lewis碱的ADS性能。研究发现,AlCl3和FeCl3显示良好的脱硫性能,且噻吩S化物的吸附活性顺序为3-MT BT DBT。其中,AlCl3对3-MT显示出极强的络合吸附能力,在正辛烷模型油中S吸附量高达141 mgS/g,在含25 wt%甲苯的模型油中的S吸附量也可达123 mgS/go同时,AlCl3也能吸附BT,并伴有BT的自聚反应,且自聚反应有利于络合吸附的进行。然而,AlCl3对DBT几乎没有吸附活性。最后,本文利用软硬酸碱理论来分析该过程的脱硫机理。研究发现,噻吩S化物既是硬碱也是软碱,S原子上与芳环平行的σ-孤对电子为硬碱区,而芳环的π-电子体系则为软碱部分。硬碱区和软碱区的电子云密度决定了其相应区域的碱性。为了提高硬酸AlCl3对软碱DBT脱除效果,论文提出了利用卤代烷烃将硬酸AlCl3软化的策略。研究发现,t-C4H9Cl、n-C4H9Cl、t-C4H9Br、 n-C4H9Br等卤代烷烃与AlCl3混合,可产生含有碳正离子的粘性液体,称其为碳正类离子液体(CPIL, carbonium pseudo ionic liquid)。对CPIL(如t-C4H9Cl-AlCl3),其中同时含有(CH3)3C+和溶解的AlCl3,且(CH3)3C+的中心C+为硬酸区,而三个-CH3的平面为软酸区,故可与噻吩硫同时具有硬酸-硬碱和软酸-软碱作用,从而显示出令人惊奇的EDS活性。只需少量的CPIL萃取剂,便可在20 min内将3-MT、BT、DBT从正辛烷模型油、含甲苯模型油中完全脱除。CPIL络合萃取过程中还伴随着部分噻吩化合物的Friedel-Crafts烷基化反应的发生。并且,CPIL能够处理组成复杂的油品(模型汽油和真油),对轻质油可实现深度脱硫,对重质油也脱除93%以上的硫化物。其次,本文还提出利用Friedel-Crafts酰基化试剂将噻吩硫(软碱)硬化的策略。氯乙酰(AC, acetyl chloride)、丙酰氯(PC, propionyl chloride)、丁酰氯(BC, butyryl chloride)和Lewis酸AlCl3,通过酰基化反应使噻吩S的芳环接上-C=O基团而被硬酸AlCl3吸附脱除,该过程被命名为酰基化脱硫(ACDS, acylation desulfurization)。研究发现,AC-AICl3组合具有极强的脱硫活性,正辛烷模型油中的噻吩(T, thiophene)、BT、DBT均可在20 min内被完全脱除。AC-AICl3优秀的ACDS活性源于酰基化反应,该反应使芳香S化物接上碱性基团-C=O,既增加了S化物的Lewis碱性,又增强了其碱硬度,这样更容易同强而硬的A1C13作用。AICl3对含甲苯油中的T、BT、DBT的S吸附量随AC的加入而变化。伴随AC的增加,AICl3对T的吸附量略微变弱,不过始终维持在120mgS/g附近；AICl3对BT的吸附量先增大后变小,最大可达75.4mgS/g; AlCl3对DBT的吸附量持续增大,从0持续上升至27.3 mgS/g。并且,ACDS对于真实油品依然有效,脱硫率可达84%以上,且硫吸附量达到56.6 mgS/g。再者,论文还研究了Lewis-Br(?)nsted混合酸对噻吩硫ODS过程的催化机理。使用Lewis酸(BF3、SnCl4、FeCl3、ZnCl2)和Bransted酸(CH3COOH)的混合酸作为催化体系,Cr(VI)或Mn(VII)为氧化剂,可实现在模型油中对DBT、BT、T的ODS过程。研究发现,Lewis酸是混合酸的核心,其跟CH3COOH中O原子发生络合作用,改善了混合酸的Bronsted酸性,促进了Cr(VI)的溶解,并催化了噻吩化合物的氧化。该过程中,DBT被氧化成DBTO2,而BT和T除了S被氧化之外,双键也被氧化,从而形成了一些复杂的氧化产物。采用量化方法计算了相关含双键物质的键级和π-轨道电子占用,分析得出这些物质的双键反应活性顺序为：苯甲苯、DBTO2 DBT T BT BTO2 TO2环己烯。最后,通过调变混合酸中的Lewis酸含量和种类,可达到调控混合酸体系酸性的目的,进而有效控制噻吩硫的氧化选择性。对于煤焦油抻酚而言,传统的碱洗法产生大量废碱,且工艺复杂,成本较高。本文基于酸碱作用,旨在通过化学吸附的方式,将苯酚从油中分离出来。论文研究了AlCl3、六次甲基四胺(HMT, hexamethylenetetramine)和三氮唑通过Lewis酸碱或氢键作用对模型油中苯酚的吸附提取性能,并对吸附规律做了实验考查和理论分析。研究发现,本文所选的吸附剂都能吸附模型油中的苯酚：HMT对酚的吸附能力最强,吸附量超过3500(mg/g-sorbent),其不溶于油且可重复利用,是一种高效的酚吸附剂；AlCl3与苯酚间为强的Lewis酸碱作用,其作用能达-111.5 kJ/mol,难以重复利用；三氮唑对酚的吸附量不大,且有油溶性。另外,萘和BT的存在不影响HMT对苯酚的吸附量,反而加速了HMT对苯酚的吸附,这是因为萘、BT分别与HMT、苯酚皆有弱的相互作用,且吸附的活化能也随两者的加入而降低。然而,喹啉的存在使HMT对苯酚的吸附量大幅降低至1000mg/g以下,因为喹啉与苯酚具有较强的相互作用,作用能达-31.2kJ/mol。最后,论文还基于现有实验数据,评价了两套Lewis酸(AlCl3和Cu(I)-Y沸石)脱硫体系的技术经济可行性。通过两套脱硫工艺过程的技术参数的估算发现,两套脱硫体系在技术上均是可行的。通过对两套脱硫工艺过程的加工成本进行核算后发现,两个脱硫体系各有所长,AlCl3体系处理Ts类硫化物的成本较低,Cu(I)-Y沸石体系则处理BTs类硫化物的成本较低。另外,通过对两套脱硫工艺过程的财务评价发现,它们在经济性上均是可行的,有进一步工业放大的前景。
[Abstract]:Oil products, mainly from petroleum refining and coal processing, including gasoline, diesel oil, coal tar, and other coal liquids, are important sources of energy and chemicals. As the weather and serious PM2.5 pollution, acid rain and so on, fuel desulfurization technology is very important. At the same time, coal tar from coal, which contains a large number of valuable chemicals, is an important organic chemical raw materials, in which the extraction of phenolic compounds has great commercial value and application prospects. The traditional hydrodesulfurization technology (HDS) is difficult to meet the increasingly stringent sulfur content standards due to its harsh reaction conditions, high loss of octane number and poor treatment effect on low sulfur oils. Therefore, many non-hydrodesulfurization technologies such as adsorptive desulfurization (ADS) and extractive desulfurization (EDS) have emerged as the times require. Desulfurization, oxidative desulfurization and so on. Based on Lewis acid-base interaction, this paper studied the desulfurization of model oil or real oil by ADS, EDS and ODS. Firstly, four kinds of Lewis acid AlCl3, FeCl3, ZnCl2 and CuCl p-3-methylthiophene (3-MT, 3-methylthiophene), benzothiophene (BT, BT, ODS) were studied. ADS properties of Lewis bases such as benzothiophene and dibenzothiophene were studied. AlCl3 and FeCl3 showed good desulfurization performance, and the order of adsorption activity of thiophene S compounds was 3-MT BT DBT. Among them, AlCl3 showed strong complex adsorption ability to 3-MT, and the adsorption capacity of S in n-octane model oil was as high as 141 mg S/g, and in 25-containing n-octane model oil. The adsorption capacity of S in wt% toluene model oil can reach 123 mg S/go. At the same time, AlCl3 can also adsorb BT with BT self-polymerization, and the self-polymerization is conducive to complexation adsorption. However, AlCl3 has little adsorption activity on DBT. Finally, the desulfurization mechanism of the process is analyzed by using the theory of hard and soft acids and bases. The_-lone pair electrons parallel to the aromatic ring on S atom are hard base and the_-lone pair electrons of aromatic ring are soft base. The density of electron cloud in hard base and soft base regions determines the alkalinity of the corresponding region. In order to improve the effect of hard acid AlCl3 on soft base DBT removal, halogenated alkanes are proposed in this paper. It is found that the mixing of halogenated alkanes such as t-C4H9Cl, n-C4H9Cl, t-C4H9Br, n-C4H9Br with AlCl3 can produce viscous liquids containing carbon cations, which are called carbon cationic ionic liquids (CPIL, carbonium pseudo ionic liquids). The hard acid region and the three-CH 3 planes are soft acid region, so they can react with thiophene sulfur simultaneously with hard acid-hard base and soft acid-soft base, thus showing surprising EDS activity. With a small amount of CPIL extractant, 3-MT, BT and DBT can be completely removed from n-octane model oil and toluene model oil in 20 minutes. With the occurrence of Friedel-Crafts alkylation of some thiophene compounds, CPIL can be used to treat complex oils (model gasoline and real oil), which can achieve deep desulfurization of light oils and removal of more than 93% of sulfides from heavy oils. Secondly, Friedel-Crafts acylation reagent is proposed to harden thiophene sulfur (soft base). The strategy. Chloroacetyl chloride (AC, acetyl chloride), propionyl chloride (PC), butyryl chloride (BC, butyryl chloride) and Lewis acid AlCl 3, by acylation reaction to make thiophene S aromatic ring on - C = O group and by hard acid AlCl 3 adsorption and removal, the process is named acylation desulfurization (ACDS, acylation desulfurization). The study found that, AC-AICl The best ACDS activity of AC-AICl3 derives from the acylation reaction, which makes the aromatic S compound join with the basic group - C=O. This reaction not only increases the Lewis alkalinity of the S compound, but also enhances its base hardness, so it is easier to be the same as the strong one. The adsorption of T, BT and DBT by AICl3 changed with the addition of AC. With the increase of AC, the adsorption of T by AICl3 weakened slightly, but remained around 120 mg S/g. The adsorption of BT by AICl3 increased first and then decreased to 75.4 mg S/g. The adsorption of DBT by AlCl3 increased continuously from 0 to 0. Furthermore, the catalytic mechanism of Lewis-Br (?) nsted mixed acid for thiophene sulfur ODS process was studied. The mixed acid of Lewis acid (BF3, SnCl4, FeCl3, ZnCl2) and Bransted acid (CH3COOH) was used as catalytic system, and Cr (VI) was used as catalytic system. It is found that Lewis acid is the core of the mixed acid. It complexes with O atom in CH3COOH, improves Bronsted acidity of the mixed acid, promotes the dissolution of Cr (VI) and catalyzes the oxidation of thiophene compounds. In addition to S being oxidized, the double bonds are also oxidized to form some complex oxidation products. The bond order and the pi-orbital electron occupation of the related double bonded substances are calculated quantitatively. The order of the double bond reactivity of these substances is as follows: benzene, DBTO2 DBT BTO 2 TO2 cyclohexene. The content and type of Lewis acid can be adjusted to control the acidity of mixed acid system, and then the oxidation selectivity of thiophene sulfur can be effectively controlled. For coal tar benzophenol, the traditional alkali washing method produces a large number of waste alkali, and the process is complex and the cost is high. In this paper, the adsorption and extraction properties of AlCl3, hexamethylenetetramine (HMT) and triazole for phenol in model oil by Lewis acid-base or hydrogen bonding were studied, and the adsorption rules were investigated experimentally and analyzed theoretically. The adsorption capacity is the strongest, the adsorption capacity is more than 3500 (mg/g-sorbent), it is insoluble in oil and can be reused, is an efficient phenol adsorbent; AlCl3 and phenol are strong Lewis acid-base interaction, its role can reach - 111.5 kJ/mol, difficult to reuse; triazole adsorption of phenol is not large, and oil-soluble. In addition, the presence of naphthalene and BT does not affect the HMT. The adsorption capacity of phenol accelerates the adsorption of phenol on HMT, because naphthalene, BT and HMT, phenol have weak interaction, and the adsorption activation energy decreases with the addition of both. However, the adsorption capacity of HMT on phenol is greatly reduced to below 1000mg/g due to the strong interaction between quinoline and phenol. Finally, based on the available experimental data, the technical and economic feasibility of two sets of Lewis acid (AlCl3 and Cu (I) - Y zeolite) desulfurization systems was evaluated. The technical parameters of the two sets of desulfurization processes were estimated to show that the two sets of desulfurization systems were technically feasible. The cost calculation shows that the two desulfurization systems have their own advantages. The cost of treating Ts sulfides by AlCl3 system is lower than that by Cu(I)-Y zeolite system, and the cost of treating BTs sulfides by Cu(I)-Y zeolite system is lower. View.
【学位授予单位】：北京化工大学
【学位级别】：博士
【学位授予年份】：2015
【分类号】：TE624.55
，
本文编号：2237165
[Abstract]:Oil products, mainly from petroleum refining and coal processing, including gasoline, diesel oil, coal tar, and other coal liquids, are important sources of energy and chemicals. As the weather and serious PM2.5 pollution, acid rain and so on, fuel desulfurization technology is very important. At the same time, coal tar from coal, which contains a large number of valuable chemicals, is an important organic chemical raw materials, in which the extraction of phenolic compounds has great commercial value and application prospects. The traditional hydrodesulfurization technology (HDS) is difficult to meet the increasingly stringent sulfur content standards due to its harsh reaction conditions, high loss of octane number and poor treatment effect on low sulfur oils. Therefore, many non-hydrodesulfurization technologies such as adsorptive desulfurization (ADS) and extractive desulfurization (EDS) have emerged as the times require. Desulfurization, oxidative desulfurization and so on. Based on Lewis acid-base interaction, this paper studied the desulfurization of model oil or real oil by ADS, EDS and ODS. Firstly, four kinds of Lewis acid AlCl3, FeCl3, ZnCl2 and CuCl p-3-methylthiophene (3-MT, 3-methylthiophene), benzothiophene (BT, BT, ODS) were studied. ADS properties of Lewis bases such as benzothiophene and dibenzothiophene were studied. AlCl3 and FeCl3 showed good desulfurization performance, and the order of adsorption activity of thiophene S compounds was 3-MT BT DBT. Among them, AlCl3 showed strong complex adsorption ability to 3-MT, and the adsorption capacity of S in n-octane model oil was as high as 141 mg S/g, and in 25-containing n-octane model oil. The adsorption capacity of S in wt% toluene model oil can reach 123 mg S/go. At the same time, AlCl3 can also adsorb BT with BT self-polymerization, and the self-polymerization is conducive to complexation adsorption. However, AlCl3 has little adsorption activity on DBT. Finally, the desulfurization mechanism of the process is analyzed by using the theory of hard and soft acids and bases. The_-lone pair electrons parallel to the aromatic ring on S atom are hard base and the_-lone pair electrons of aromatic ring are soft base. The density of electron cloud in hard base and soft base regions determines the alkalinity of the corresponding region. In order to improve the effect of hard acid AlCl3 on soft base DBT removal, halogenated alkanes are proposed in this paper. It is found that the mixing of halogenated alkanes such as t-C4H9Cl, n-C4H9Cl, t-C4H9Br, n-C4H9Br with AlCl3 can produce viscous liquids containing carbon cations, which are called carbon cationic ionic liquids (CPIL, carbonium pseudo ionic liquids). The hard acid region and the three-CH 3 planes are soft acid region, so they can react with thiophene sulfur simultaneously with hard acid-hard base and soft acid-soft base, thus showing surprising EDS activity. With a small amount of CPIL extractant, 3-MT, BT and DBT can be completely removed from n-octane model oil and toluene model oil in 20 minutes. With the occurrence of Friedel-Crafts alkylation of some thiophene compounds, CPIL can be used to treat complex oils (model gasoline and real oil), which can achieve deep desulfurization of light oils and removal of more than 93% of sulfides from heavy oils. Secondly, Friedel-Crafts acylation reagent is proposed to harden thiophene sulfur (soft base). The strategy. Chloroacetyl chloride (AC, acetyl chloride), propionyl chloride (PC), butyryl chloride (BC, butyryl chloride) and Lewis acid AlCl 3, by acylation reaction to make thiophene S aromatic ring on - C = O group and by hard acid AlCl 3 adsorption and removal, the process is named acylation desulfurization (ACDS, acylation desulfurization). The study found that, AC-AICl The best ACDS activity of AC-AICl3 derives from the acylation reaction, which makes the aromatic S compound join with the basic group - C=O. This reaction not only increases the Lewis alkalinity of the S compound, but also enhances its base hardness, so it is easier to be the same as the strong one. The adsorption of T, BT and DBT by AICl3 changed with the addition of AC. With the increase of AC, the adsorption of T by AICl3 weakened slightly, but remained around 120 mg S/g. The adsorption of BT by AICl3 increased first and then decreased to 75.4 mg S/g. The adsorption of DBT by AlCl3 increased continuously from 0 to 0. Furthermore, the catalytic mechanism of Lewis-Br (?) nsted mixed acid for thiophene sulfur ODS process was studied. The mixed acid of Lewis acid (BF3, SnCl4, FeCl3, ZnCl2) and Bransted acid (CH3COOH) was used as catalytic system, and Cr (VI) was used as catalytic system. It is found that Lewis acid is the core of the mixed acid. It complexes with O atom in CH3COOH, improves Bronsted acidity of the mixed acid, promotes the dissolution of Cr (VI) and catalyzes the oxidation of thiophene compounds. In addition to S being oxidized, the double bonds are also oxidized to form some complex oxidation products. The bond order and the pi-orbital electron occupation of the related double bonded substances are calculated quantitatively. The order of the double bond reactivity of these substances is as follows: benzene, DBTO2 DBT BTO 2 TO2 cyclohexene. The content and type of Lewis acid can be adjusted to control the acidity of mixed acid system, and then the oxidation selectivity of thiophene sulfur can be effectively controlled. For coal tar benzophenol, the traditional alkali washing method produces a large number of waste alkali, and the process is complex and the cost is high. In this paper, the adsorption and extraction properties of AlCl3, hexamethylenetetramine (HMT) and triazole for phenol in model oil by Lewis acid-base or hydrogen bonding were studied, and the adsorption rules were investigated experimentally and analyzed theoretically. The adsorption capacity is the strongest, the adsorption capacity is more than 3500 (mg/g-sorbent), it is insoluble in oil and can be reused, is an efficient phenol adsorbent; AlCl3 and phenol are strong Lewis acid-base interaction, its role can reach - 111.5 kJ/mol, difficult to reuse; triazole adsorption of phenol is not large, and oil-soluble. In addition, the presence of naphthalene and BT does not affect the HMT. The adsorption capacity of phenol accelerates the adsorption of phenol on HMT, because naphthalene, BT and HMT, phenol have weak interaction, and the adsorption activation energy decreases with the addition of both. However, the adsorption capacity of HMT on phenol is greatly reduced to below 1000mg/g due to the strong interaction between quinoline and phenol. Finally, based on the available experimental data, the technical and economic feasibility of two sets of Lewis acid (AlCl3 and Cu (I) - Y zeolite) desulfurization systems was evaluated. The technical parameters of the two sets of desulfurization processes were estimated to show that the two sets of desulfurization systems were technically feasible. The cost calculation shows that the two desulfurization systems have their own advantages. The cost of treating Ts sulfides by AlCl3 system is lower than that by Cu(I)-Y zeolite system, and the cost of treating BTs sulfides by Cu(I)-Y zeolite system is lower. View.
【学位授予单位】：北京化工大学
【学位级别】：博士
【学位授予年份】：2015
【分类号】：TE624.55
，
本文编号：2237165
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