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甲醛制备方法

网址:www.chujiaquan58.com  2019-12-09  作者:admin    阅读:

甲醛制备方法
Formaldehyde preparation method
甲醛用途广泛,属生产工艺简单、原料供应充足的大众化工产品。是甲醇下游产品树中的主干,世界30%左 右的甲醇都用来生产甲醛,年产量在2500万吨左右。甲醛溶液是一种浓度较低的水溶液,从经济角度考虑不便于长距离运输,所以一般都在主消费市场附近设厂.进出口贸易也极少。工业上主要采用甲醇氧化法和天然气直接氧化法生产 [4]  。
Formaldehyde is widely used as a popular chemical product with simple production process and sufficient supply of raw materials. It is the backbone of methanol downstream product trees. About 30% of the world's methanol is used to produce formaldehyde, with an annual output of about 25 million tons. Formaldehyde solution is a kind of aqueous solution with low concentration, which is not convenient for long-distance transportation from an economic point of view. Therefore, factories are generally set up near the main consumer market, and there is little import and export trade. In industry, methanol oxidation method and natural gas direct oxidation method are mainly used for production [4].
1、甲醇氧化法:在600~700℃下,使甲醇、空气和水通过银、铜或五氧化二矾等催化剂,直接氧化生成甲醛,用水吸收得甲醛溶液:
1. Methanol oxidation method: at 600 ~ 700 ℃, methanol, air and water are directly oxidized to formaldehyde through catalysts such as silver, copper or alum pentoxide, which is absorbed by water to obtain formaldehyde solution
总反应是放热反应,但50~60%的甲醛是通过氧化反应生成,而其
The total reaction is exothermic, but 50-60% formaldehyde is formed by oxidation reaction
余部分是通过氢反应生成。副产物为一氧化碳和二氧化碳、甲酸甲酯及甲酸。甲醇转化率80%,收率以甲醇计为85%~90%。该法技术成熟,收率高,国内外生产厂广为采用。 [4]
The rest is formed by hydrogen reaction. By products are carbon monoxide and carbon dioxide, methyl formate and formic acid. The conversion rate of methanol is 80%, and the yield is 85% ~ 90%. The technology of this method is mature and the yield is high. [4]
2、天然气氧化法:在600-680℃下,使天然气和空气的混合物通过铁、钼等的氧化物催化剂,直接氧化生成甲醛,用水吸收得甲醛溶液: [4]
2. Natural gas oxidation method: at 600-680 ℃, the mixture of natural gas and air is directly oxidized to formaldehyde through oxide catalysts such as iron and molybdenum, and the formaldehyde solution is obtained by absorption of water: [4]
3、二甲醚氧化法:系采用合成气高压法合成甲醇的副产物二甲醚为原料,以金属氧化物为催化剂氧化而成。
3. Dimethyl ether oxidation method: it is made of dimethyl ether, the by-product of methanol synthesis by high-pressure synthetic gas method, and metal oxide as catalyst.
4、将甲醇蒸气在300℃时,用铜或银的催化剂,使甲醇脱氢氧化制得。甲醛气体吸收水含量达36%~40%,即为甲醛溶液。将市售甲醛溶液蒸馏去除杂质,并补充甲醇即为试剂甲醛溶液: [4]
4. When the methanol vapor is at 300 ℃, the methanol is dehydrogenated and oxidized with the catalyst of copper or silver. Formaldehyde gas absorbs 36% - 40% water, which is formaldehyde solution. Distill the formaldehyde solution on sale to remove impurities, and add methanol as the reagent formaldehyde solution: [4]
5、甲醇脱氢法:甲醇直接脱氢可得到无水甲醛,同时副产氢气。该工艺是极具吸引力的甲醛制备方法。其进展关键在于催化剂性能的提高。
5. Methanol dehydrogenation method: anhydrous formaldehyde can be obtained by direct dehydrogenation of methanol, and hydrogen can be produced at the same time. This process is an attractive method to prepare formaldehyde. The key to its development lies in the improvement of catalyst performance.
6、将气化的甲醇与经碱洗后的空气、水蒸气以1∶1.8-2.0∶0.8-1.0( 体积比)混合后,加热至115-120℃进行反应,在银催化剂作用下控制反应温度为600-650℃,压力0.3-0.5MPa:
6. Mix the gasified methanol with the air and steam after alkali washing in the ratio of 1:1.8-2.0:0.8-1.0 (volume ratio), and heat to 115-120 ℃ for reaction. Under the action of silver catalyst, control the reaction temperature to 600-650 ℃, and pressure to 0.3-0.5mpa
反应结束后,将反应物急冷至80-85℃,用水吸收,然后蒸馏,蒸出未反应的甲醇,釜液经阴离子交换树脂处理,所得甲醛溶液加入适量阻聚剂,搅拌混合,即得成品。
After the reaction, quench the reactant to 80-85 ℃, absorb it with water, distill it, evaporate the unreacted methanol, treat the kettle liquid with anion exchange resin, add a proper amount of polymerization inhibitor into the formaldehyde solution, mix it, and the finished product is obtained.

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