Method for preparation of n-docosane by natural acid-behenic acid

Abstract

The invention relates to a method for preparation of n-docosane by natural acid-behenic acid, a behenic acid raw material is mixed with a solvent for hydrogenation reaction in the presence of a catalyst and hydrogen, the catalyst is a palladium / carbon nanotube catalyst, the hydrogen contains 5-50 mu L / L of NH3, the hydrogenation reaction pressure is 1-10MPa, the reaction temperature 220-320 DEG C, and the reaction time is 3-10h. The catalyst uses multi-wall carbon nanotube as a carrier, and 2%-10% by mass of palladium as an active component; the solvent is one of n-hexane, n-heptane, n-octane or dodecane. Compared with the prior art, the method has the advantages of simple preparation process, low reaction temperature, less solvent consumption, high reaction activity and higher yield of an objective product.

Description

technical field [0001] The invention relates to a method for generating n-docosane through liquid-phase catalytic hydrodeoxygenation of behenic acid, which belongs to the field of catalytic technology. Background technique [0002] As one of the key components of low-temperature diesel oil improvers and environmentally friendly liquid fuel compositions, n-paraffins have been widely used. important role. [0003] The preparation method of existing n-alkane mainly contains the following several kinds: one, adopt molecular sieve or urea dewaxing to prepare the mixture of n-alkane, then carry out the method of subsection freezing, separation n-alkane monomer, wherein typical process There is an IVDW process developed by our country; 2. The Wurtz reaction is used to prepare symmetrical n-alkanes; 3. The iodoalkane reduction method is used; 4. Petroleum ether, n-hexane, and n-heptane are used as solvents to link halogenated alkanes. Although the above methods can obtain the corr...

AI Technical Summary

Problems solved by technology

Although the above methods can obtain the corresponding n-alkane monomers, there are certain problems in each method: as the first method, the process conditions are more complicated, and the requirements for some equipment and materials are very high; the second method is only applicable For symmetrical even-numbered alkanes, the resulting products need to be extracted repeatedly with ether solvent; the third and fourth methods are very dangerous to operate, and petroleum ether is very easy to erupt in the violent reaction between metal sodium and halogenated alkanes, with low safety factor and high cost

[0005] The corresponding alkanes can be prepared by hydrogenation of higher fatty acid esters, but during the hydrogenation reaction, a large number of decarboxylation and decarbonylation reactions will occur, making the composition of the reaction product complex and producing more alkanes with reduced carbon numbers. On the one hand, it is not conducive to improving the yield of the target product. On the other hand, the decarboxylation reaction and decarbonylation reaction will produce carbon monoxide or carbon dioxide, which will have an adverse effect on the hydrogenation reaction.

[0006] CN200910100260.5 discloses a method for preparing alkanes from higher fatty acid esters, using fatty acid methyl esters containing 8 to 22 carbon atoms or fatty acid ethyl esters containing 8 to 22 carbon atoms as raw materials for hydrogenation reaction to produce alkanes, However, it can be seen that in the obtained alkane products, most of the carbon in the fatty acid is still removed, such as using methyl stearate (stearic acid is octadecyl carboxylic acid) as raw material, the obtained heptadecane The total yield of octadecanes and octadecanes is only 75%, therefore, the yield of non-decarburized direct hydrogenation products (octadecanes) will be lower

At the same time, the difference between the boiling points of heptadecanes and octadecanes is very small, and it is very difficult to further obtain octadecanes through separation technology

However, the technology of producing n-docosane by hydrogenation method has not been reported yet.