正丁烷法順酐工藝按反應器分為固定床工藝和流化床工藝，其后處理工段所采用的工藝有兩種技術方法，即水吸收法和溶劑吸收法。
The production process of n-butane maleic anhydride is divided into fixed bed process and fluidized bed process according to the reactor. There are two technical methods used in the subsequent treatment section, namely water absorption method and solvent absorption method.
1. 丁烷法固定床工藝：丁烷法固定床工藝主要由亨斯邁公司、BP、SD、 與苯氧化法基本相似，但正丁烷氧化轉化率和選擇性均比苯低，其順酐的摩爾收率按正丁烷計僅為 50％~55％，而原料氣體中苯和正丁烷的摩爾濃度基本相同。因此對于同樣規模的裝置，正丁烷法需要較大的反應器和壓縮機。反應溫度 400～450℃，壓力為 125～130 MPa。為了降低正丁烷的單耗，比利時的 Pantochim公司采用尾氣循環工藝，吸收塔頂出來的尾氣約50％經處理后與新鮮空氣一并進入反應器。該工藝可使正丁烷的單耗下降約 10％ 。
1. Butane fixed bed process: The butane fixed bed process is mainly composed of Huntsman, BP, SD, and is basically similar to the benzene oxidation method, but the conversion rate and selectivity of n-butane oxidation are lower than benzene. The molar yield of maleic anhydride is only 50%~55% based on n-butane, while the molar concentration of benzene and n-butane in the raw gas is basically the same. Therefore, for production units of the same scale, the n-butane method requires larger reactors and compressors. The reaction temperature is 400-450 ℃, and the pressure is 125-130 MPa. In order to reduce the unit consumption of n-butane, Pantochim Company in Belgium adopts a tail gas circulation process. About 50% of the tail gas from the top of the absorption tower is treated and enters the reactor together with fresh air. This process can reduce the unit consumption of n-butane by about 10%.
2. 丁烷法流化床工藝：流化床工藝是 Lummus 公司和 Lonza 公司合作開發的 ALMA 工藝。 流化床反應器中，正丁烷和空氣分別進入反應器后混合，避免了其混合時發生爆炸的可能 因此原料氣中正丁烷的摩爾分數可以提高到 4％，反應所需空氣約為固定床的一半，減少了空氣壓縮機的投資和操作費用。流化床工藝的能耗低于固定床，但丁烷的單耗要比固定床高約 8％，另外流化床催化劑的磨損也較大。
2. Butane method fluidized bed process: The fluidized bed process is an ALMA process jointly developed by Lummus and Lonza companies. In a fluidized bed reactor, n-butane and air are mixed separately after entering the reactor, avoiding the possibility of explosion during mixing. Therefore, the molar fraction of n-butane in the feed gas can be increased to 4%, and the required air for the reaction is about half of that of a fixed bed, reducing the investment and operating costs of the air compressor. The energy consumption of the fluidized bed process is lower than that of the fixed bed, but the unit consumption of butane is about 8% higher than that of the fixed bed, and the wear of the fluidized bed catalyst is also significant.
3. 有機溶劑吸收法工藝：在采用丁烷法順酐的初期，主要是一些苯法裝置通過更換催化劑實現，就是新建的裝置工藝也與苯法基本一致，均為水吸收法回收。由于丁烷氧化反應生成少量的乙酸和丙烯酸，而苯氧化反應幾乎不生成乙酸和丙烯酸，另外丁烷氧化生成的水也比苯氧化多 1 倍，所以丁烷法水吸收工藝遇到的腐蝕和堵塞問題要比苯法多。
3. Organic solvent absorption process: In the early stages of using the butane method to produce maleic anhydride, some benzene process units were mainly achieved by replacing catalysts, and even the newly built unit process was basically the same as the benzene process, all of which were recovered by water absorption method. Due to the butane oxidation reaction generating a small amount of acetic acid and acrylic acid, while the benzene oxidation reaction hardly generates acetic acid and acrylic acid, and the amount of water generated by butane oxidation is also twice that of benzene oxidation, the butane method water absorption process encounters more corrosion and blockage problems than the benzene method.
為了減輕腐蝕 提高順酐收率，降低能耗，各公司在改進丁烷氧化催化劑的同時 加強了對順酐回收工藝的研究。溶劑吸收工藝采用低揮發性有機溶劑，順酐收率比水吸收工藝約高 5％。ALMA 工藝采用六氫鄰苯二甲酸二異丁酯（DIBE ，Huntsman 公司和 Conser 公司采用鄰苯二甲酸二正丁酯（DBP）。 在工業中，這兩種溶劑的消耗接近，DIBE 溶劑處理需進行水洗和堿洗兩個過程， 而 DBP 溶劑僅需水洗。 另外， DIBE 的要高于 DBP。
In order to reduce corrosion, improve the yield of maleic anhydride, and reduce energy consumption, various companies have strengthened their research on the recovery process of maleic anhydride while improving butane oxidation catalysts. The solvent absorption process uses low volatile organic solvents, and the yield of maleic anhydride is about 5% higher than that of water absorption process. The ALMA process uses Diisobutyl Hexahydrophthalate (DIBE), while Huntsman and Consumer use Diisobutyl Phthalate (DBP). In industrial production, the consumption of these two solvents is similar. DIBE solvent treatment requires two processes: water washing and alkali washing, while DBP solvent only requires water washing. In addition, the price of DIBE is higher than that of DBP.
