固定床气相氧化偏三甲苯制偏苯三甲酸酐的方法
Method for producing trimellitic anhydride by gas-phase oxidation of trimellitic benzene in fixed bed
技术领域：本发明涉及一种偏苯三甲酸酐的制造方法。Technical field: the present invention relates to a kind of manufacture method of trimellitic anhydride.
背景技术：偏苯三甲酸酐(Trimellitic anhydride)，简称偏酐，是一种重要的化工原料，广泛地应用于耐高温增塑剂、聚酯树脂、聚酯环氧粉末涂料、绝缘漆、水溶性醇酸树脂、润滑油、油墨、胶粘剂等生产行业。目前世界上偏苯三甲酸酐生产主要以美国和日本为代表的偏三甲苯液相氧化技术为主，占世界上总产量的70％左右。该工艺是以偏三甲苯为原料，在醋酸介质中，以Co-Mn-Br为催化剂，约2Mpa压力下，用空气氧化制成偏苯三甲酸酐。此工艺路线收率高，但流程长，对设备防腐、自控等方面要求苛刻，相对投资额大，生产维修费用高。国内现有液相氧化生产装置多套，总设计生产能力约1.5万吨。由于国内现有技术尚不完善，设备腐蚀严重，其开工率仅有30％左右，无法满足国内偏苯三甲酸酐市场需求。国内大连理工大学、鞍山化工所曾进行过偏三甲苯气相氧化制偏苯三甲酸酐的研究，采用V-Ti-P-O体系催化剂，其粗酐重量收率最高可达55.6％。Background technology: Trimellitic anhydride (Trimellitic anhydride), referred to as partial anhydride, is an important chemical raw material, widely used in high temperature resistant plasticizers, polyester resins, polyester epoxy powder coatings, insulating varnishes, water-soluble Alkyd resin, lubricating oil, ink, adhesive and other production industries. At present, the production of trimellitic anhydride in the world is mainly based on the liquid-phase oxidation technology of trimellitic acid represented by the United States and Japan, accounting for about 70% of the world's total output. The process uses trimellitic benzene as raw material, in acetic acid medium, with Co-Mn-Br as catalyst, under the pressure of about 2Mpa, trimellitic anhydride is produced by air oxidation. This process route has a high yield, but the process is long and has strict requirements on equipment anti-corrosion and automatic control, relatively large investment, and high production and maintenance costs. There are many sets of domestic liquid phase oxidation production equipment, with a total design production capacity of about 15,000 tons. Due to the incomplete domestic technology and serious equipment corrosion, its operating rate is only about 30%, which cannot meet the domestic market demand for trimellitic anhydride. Domestic Dalian University of Technology and Anshan Institute of Chemical Industry have conducted studies on the production of trimellitic anhydride by gas-phase oxidation of trimellitic toluene. Using V-Ti-P-O system catalyst, the weight yield of crude anhydride can reach up to 55.6%.
发明内容：为解决目前采用液相氧化技术生产偏苯三甲酸酐所存在的设备腐蚀严重、收率低的问题，本发明提供一种固定床气相氧化偏三甲苯制偏苯三甲酸酐的方法。本发明的方法是：将偏三甲苯、水蒸汽和空气混合送入装有钒-钛系固定床催化剂的管形反应器中，使偏三甲苯被氧化成偏苯三甲酸酐；反应条件为：水蒸气与偏三甲苯进料体积比为1∶5～40，催化剂负荷为10～100g/L·h，空速为1000～10000L/L·h，反应温度为350～450℃。上述反应所用的管形反应器的内径为20～30mm，最佳为25mm。夹带偏苯三甲酸酐蒸气的反应气在捕集器中被冷却，偏苯三甲酸酐以结晶状固体析出，并在捕集器中被收集。尾气通过水吸收瓶后放空。捕集器经空气吹干至恒重，用差减法称量出固体粗产品量。水吸收瓶用碱滴定法测定其粗酐含量。两者之和为反应所得粗酐量。反应最佳条件为：水蒸汽与偏三甲苯进料体积比最好为1∶10～30；催化剂负荷最好为20～50g/L·h；空速最好为2000～5000L/L·h；反应温度最好为360～420℃。本发明使用涂层型球状或环状催化剂。载体为惰性的SiC、α-Al2O3或耐酸陶瓷，加工成φ4-6mm的球状或内径4mm、外径6mm、长6mm的环状。催化剂活性组份以V2O5和TiO2为主，另外还含有P2O5及Na2O、K2O、Rb2O、Cs2O其中一种或多种。可用作催化剂制备活性组份的物质由A、B、C、D组成，A：NH4VO3或V2O5；B：TiCl4或TiO2；C：NH4H2PO4；D：Na、K、Rb或Cs碱金属的硝酸盐、硫酸盐或碳酸盐中的一种或多种。催化剂活性物质的重量比为：V2O5∶TiO2∶P2O5∶X2O＝5～25∶75～95∶0.1～4.5∶0.01～0.5，式中X为Na、K、Rb、Cs其中的一种或多种。催化剂具体制备方法是，首先将草酸溶解在蒸馏水中，然后加入NH4VO3或V2O5加热溶解；再用少量蒸馏水溶解NH4H2PO4和碱金属盐，加入上述NH4VO3或V2O5溶液中；在50～60℃温度下搅拌30分钟，然后用水冷却，慢慢向该溶液中滴加TiCl4或者将锐钛型TiO2加适量水研磨后加入该溶液；充分搅拌制成活性组份浆状液；在设有外部加热的转鼓中放入载体，将上述浆状液均匀地喷涂在载体上，喷涂量为载体重量的10～15％，然后将喷涂好的催化剂在550℃热空气流中焙烧6-8小时即制成催化剂。所用的碱金属盐为K2CO3、Cs2SO4、RbNO3、Na2CO3其中一种或多种，本发明可使粗酐重量收率达到100％以上，最高可达107％。本发明的制偏苯三甲酸酐的方法对设备腐蚀低，工艺流程简单，并易于形成工业化生产。本发明的气相氧化工艺过程简单，常压操作，无腐蚀，具有液相氧化工艺无可比拟的优越性。Summary of the invention: In order to solve the problems of severe equipment corrosion and low yield in the current production of trimellitic anhydride by liquid phase oxidation technology, the present invention provides a method for producing trimellitic anhydride by gas-phase oxidation of trimellitic anhydride in a fixed bed. The method of the present invention is: the trimellitylene, water vapor and air are mixed and sent into a tubular reactor equipped with a vanadium-titanium fixed-bed catalyst, so that the trimellitylene is oxidized into trimellitic anhydride; the reaction conditions are: The feed volume ratio of water vapor to mesitylene is 1:5-40, the catalyst load is 10-100g/L·h, the space velocity is 1000-10000L/L·h, and the reaction temperature is 350-450°C. The inner diameter of the tubular reactor used in the above reaction is 20-30 mm, preferably 25 mm. The reaction gas entraining the trimellitic anhydride vapor is cooled in the trap, and the trimellitic anhydride is precipitated as a crystalline solid and is collected in the trap. The exhaust gas is vented after passing through the water absorption bottle. The trap is dried by air to constant weight, and the amount of solid crude product is weighed by subtraction method. The crude anhydride content of the water absorption bottle was determined by alkali titration. The sum of the two is the amount of crude anhydride obtained from the reaction. The optimum conditions for the reaction are: the volume ratio of water vapor to trimethylbenzene is preferably 1:10-30; the catalyst load is preferably 20-50 g/L h; the space velocity is preferably 2000-5000 L/L h ; The reaction temperature is preferably 360-420°C. The present invention uses coated spherical or ring catalysts. The carrier is inert SiC, α-Al 2 O 3 or acid-resistant ceramics, processed into a spherical shape of φ4-6mm or a ring shape with an inner diameter of 4mm, an outer diameter of 6mm, and a length of 6mm. The catalyst active components are mainly V 2 O 5 and TiO 2 , and also contain P 2 O 5 and one or more of Na 2 O, K 2 O, Rb 2 O, and Cs 2 O. The substances that can be used as catalysts to prepare active components are composed of A, B, C, D, A: NH 4 VO 3 or V 2 O 5 ; B: TiCl 4 or TiO 2 ; C: NH 4 H 2 PO 4 ; D : One or more of nitrates, sulfates or carbonates of Na, K, Rb or Cs alkali metals. The weight ratio of catalyst active material is: V 2 O 5 : TiO 2 : P 2 O 5 : X 2 O=5～25:75～95:0.1～4.5:0.01～0.5, where X is Na, K, Rb , Cs one or more of them. The specific preparation method of the catalyst is as follows: first dissolve oxalic acid in distilled water, then add NH 4 VO 3 or V 2 O 5 to heat and dissolve; then dissolve NH 4 H 2 PO 4 and alkali metal salt with a small amount of distilled water, add the above NH 4 VO or V 2 O 5 solution; stir at 50-60°C for 30 minutes, then cool with water, slowly add TiCl 4 to the solution or grind anatase TiO 2 with appropriate amount of water and add to the solution; fully Stir to make the active component slurry; put the carrier in the drum with external heating, spray the above slurry evenly on the carrier, the spraying amount is 10-15% of the weight of the carrier, and then spray the The catalyst is calcined in a hot air stream at 550°C for 6-8 hours to make the catalyst. The alkali metal salt used is one or more of K 2 CO 3 , Cs 2 SO 4 , RbNO 3 , and Na 2 CO 3 , and the present invention can make the crude anhydride weight yield more than 100%, and the highest can reach 107%. The method for preparing trimellitic anhydride of the present invention has low equipment corrosion, simple process flow and easy industrialized production. The gas-phase oxidation process of the present invention is simple, operated under normal pressure, free from corrosion, and has incomparable advantages over the liquid-phase oxidation process.
具体实施方式一：以NH4VO3、CsNO3、NH4H2PO4和TiCl4为原料，以φ4-6mm的SiC球为载体，制成活性组份重量比为V2O5∶TiO2∶P2O5∶Cs2O＝8.60∶86.42∶2.83∶0.15的催化剂。取50ml装入内径25mm玻璃反应管中，在反应温度400℃，水蒸汽∶偏三甲苯＝20，催化剂负荷35g/L·h，空速3000L/L·h操作条件下，粗偏苯三甲酸酐重量收率为98.7％。Specific embodiment one: NH 4 VO 3 , CsNO 3 , NH 4 H 2 PO 4 and TiCl 4 are used as raw materials, and SiC balls with a diameter of 4-6mm are used as carriers to make active components with a weight ratio of V 2 O 5 : TiO 2 :P 2 O 5 :Cs 2 O=8.60:86.42:2.83:0.15 catalyst. Get 50ml and pack in the glass reaction tube of inner diameter 25mm, at reaction temperature 400 ℃, steam: trimethylene=20, catalyst load 35g/L h, under the operating condition of space velocity 3000L/L h, thick trimellitic anhydride The weight yield was 98.7%.
具体实施方式二：以NH4VO3、RbNO3、K2CO3、NH4H2PO4和TiCl4为原料，以内径4mm、外径6mm、长6mm的α-Al2O3环为载体，制成活性组份重量比为V2O5∶TiO2∶P2O5∶Rb2O∶K2O＝10.56∶86.71∶2.50∶0.12∶0.11的催化剂。取50ml装入内径25mm玻璃反应管中，在反应温度395℃，水蒸汽∶偏三甲苯＝25，催化剂负荷34.5g//L·h，空速3500L/L·h操作条件下，相对偏三甲苯粗偏苯三甲酸酐重量收率为107％，由捕集器得到的粗偏苯三甲酸酐纯度为96.8％。Specific embodiment two: NH 4 VO 3 , RbNO 3 , K 2 CO 3 , NH 4 H 2 PO 4 and TiCl 4 are used as raw materials, and an α-Al 2 O 3 ring with an inner diameter of 4 mm, an outer diameter of 6 mm and a length of 6 mm is used as the The carrier is made into a catalyst whose active component weight ratio is V 2 O 5 :TiO 2 : P 2 O 5 :Rb 2 O :K 2 O=10.56:86.71:2.50:0.12:0.11. Take 50ml and put it into a glass reaction tube with an inner diameter of 25mm. Under the operating conditions of reaction temperature 395°C, water vapor: trimethylene = 25, catalyst load 34.5g//L h, and space velocity 3500L/L h, the relative partial trimethylbenzene The weight yield of toluene crude trimellitic anhydride was 107%, and the purity of the crude trimellitic anhydride obtained by the trap was 96.8%.
具体实施方式三：以NH4VO3、TiO2(锐钛型)、NH4H2PO4、RbNO3和K2CO3为原料，以在实施例二同样载体制成活性组份重量比为V2O5∶TiO2∶P2O5∶Rb2O∶K2O＝8.55∶86.70∶2.55∶0.10∶0.10的氧化催化剂。取50ml装入内径25mm玻璃反应管中，在反应温度405℃，水蒸汽∶偏三甲苯＝22，催化剂负荷35g/L·h，空速3500L/L·h操作条件下，粗偏苯三甲酸酐重量收率为98.9％。Specific embodiment three: use NH 4 VO 3 , TiO 2 (anatase type), NH 4 H 2 PO 4 , RbNO 3 and K 2 CO 3 as raw materials, and use the same carrier as in Example 2 to make the active component weight ratio It is an oxidation catalyst of V 2 O 5 :TiO 2 :P 2 O 5 :Rb 2 O :K 2 O=8.55:86.70:2.55:0.10:0.10. Get 50ml and pack in the glass reaction tube of inner diameter 25mm, at reaction temperature 405 ℃, steam: trimetylene=22, catalyst load 35g/L h, under the operating conditions of space velocity 3500L/L h, thick trimellitic anhydride The weight yield was 98.9%.