Highly Efficient Synthesis Of Polyalkylated Naphthalenes Catalyzed By Acidic Ionic Liquids And Their Lubrication

Naphthalene is one of the most important chemicals in coal coking industry,which is mainly used for the production of water reducing agent of cement.With the advent of the new polycarboxylic acid water-reducing agents,the downstream products of naphthalene are seriously affected,and the price of the industrial naphthalene prices traded at a lower price,leading to the serious overcapacity of naphthalene.Using naphthalene as starting raw for producing useful chemicals can not only improve the utilization value of naphthalene,but also alleviate the overcapacity problem of naphthalene.Naphthalene could be used to produce different naphthalene-based chemicals through a typical Friedel-Crafts reaction,the physicochemical properties and application of alkyl naphthalene chemicals depend on the molecular structure and the number of side chains.In this paper,the acidic ionic liquids were used as catalyst for the naphthalene alkylation,and a series of polyalkylated naphthalene products was achieved through the alkylation reaction of naphthalene with medium-long-chain?-olefins?n-butene,n-hexene and n-octene?,respectively.The effect of structure and component of ionic liquids on naphthalene alkylation was studied in detail.Compared to the cycloalkyl lubricating oil,we studied the physicochemical properties,rheological properties and tribological performance for the polyalkylated naphthalenes as a lubricating base oil,and revealed the structure-activity relationship of alkyl naphthalene as lubricating base oil.The experimental results provide the theoretical guidance to some extent for the synthesis and application of naphthalene-based lubricants.The main contents and conclusions for this thesis are described as follows:1.Alkylation of naphthalene with n-hexene/n-octene over different acidic ionic liquids was carried out.The different ionic liquid catalysts were investigated with an aim to obtain a highly efficient catalyst,and the acidity of the catalyst was characterized.The effects of reaction conditions,including X_AlCl3,the amount of catalyst,olefins and naphthalene mole ratio,olefins droptime,reaction temperature and reaction time,on the reaction results were investigated.And a convincible mechanism was proposed for the alkylation over the ionic liquid Et₃NHCl-AlCl₃ with a good recyclability.The reaction products were analyzed and mainly consisted of poly-hexylnaphthalenes/poly-octylnaphthalenes?the isomer of tri-/tetra-hexylnaphthalenes and the isomer of tri-/tetra-octylnaphthalenes,respectively?.Under the optimal conditions,the conversion rate of naphthalene was 100%,the selectivity of poly-hexyl/octylnaphthalenes was 98%,and the ionic liquid Et₃NHCl-AlCl₃ was effectively repeated for five times without obvious inactivation.2.Butene is a by-product of methanol production of low carbon alkenes,the alkylation of naphthalene with n-butene was carried out using Et₃NHCl-AlCl₃ as catalyst.The effects of reaction conditions,includingX_AlCl3=0.67,the amount of catalyst,n-butene flow rate,reaction temperature and reaction time on the reaction results were investigated.The quantitative and qualitative analysis of the products and the reuse efficiency of ionic liquid Et₃NHCl-AlCl₃ were investigated.The results showed that the reaction products were poly-butylnaphthalenes?the isomersoftri-butylnaphthalenes,tetra-butylnaphthalenes,penta-butylnaphthalenes and hexa-butylnaphthalenes,respectively?.Under the optimal conditions,the conversion rate of naphthalene was 100%,and the selectivity of poly-butylnaphthalenes?tri/tetra/penta/hexa-butylnaphthalenes?was 100%,the tetra-butylnaphthalenes as the main component accounted for 86%.3.Based on the synthesized polyalkylated naphthalene products as mentioned above,the basic physicochemical properties for the products,such as the kinematic viscosity,viscosity index,flash point,pour point,aniline point,initial oxidation temperature,color and rheological properties and the tribological properties were systematically studied in this paper.The results showed that alkyl naphthalenes as the lubricating base oil had a close correlation between its physicochemical properties and the length of the side chain.Generally,the long the alkyl chain affords the high viscosity for the polyalkylated naphthalenes,and the viscosity-temperature performance is not good for the short alkyl side-chain.In terms of the tribological properties,the anti-friction and anti-wear properties of poly-butylnaphthalenes were the worst,followed by poly-hexylnaphthalenes.The anti-friction and anti-wear properties of poly-octylnaphthalenes is similar to cycloalkyl lubricating oil.