微波法合成乙二醇插层镍铝层状双金属氢氧化物

乙二醇(EG)插层层状双金属氢氧化物(LDH)可作为层间催化反应器,用于原油中环烷酸与EG的酯化脱酸反应,但其合成过程需要较长时间。以硝酸根型镍铝LDH为前体,在KOH促进下,采用微波辅助的离子交换法合成EG插层LDH,省时节能,提高效率。考察了微波时间、微波温度和微波功率对EG插层LDH结构的影响。并用XRD、FT-IR和TG-DSC等比较了微波法和常规方法合成的EG插层LDH的性质。结果表明,微波辐射能提供高能量,促进待交换阴离子向层间的扩散,并减弱层板与层间原有阴离子间的作用力,在微波温度为120℃,微波时间为10 min和微波功率550 W的条件下,即可得到结晶度高的EG插层LDH。微波法合成的EG插层LDH与常规方法合成的具有相似的性质和更高的结晶度,而合成时间可由12 h大幅缩短至10 min。

Microwave Assisted Synthesis of Ethylene Glycol Intercalated Nickel-aluminum Layered Double Hydroxides

Ethylene glycol(EG) intercalated layered double hydroxide(LDH) can be used as an interlayer catalytic reactor for the esterification of naphthenic acids with EG in oil. However, long synthesis time for EG intercalated LDH limits its further application. In the present investigation, EG intercalated NiAl-LDH was synthesized via a microwave-assisted ion exchange method by the aid of KOH and with nitrate LDH as precursor. The effects of microwave irradiating time and power, and the reaction temperature on the structure of EG intercalated LDH were investigated. XRD, FT-IR and TG-DSC were used to characterize EG intercalated LDHs prepared. Microwave irradiation was found to provide sufficient energy to accelerate the diffusion of exchanging anions into the interlayer and weaken the interaction between the layers and original interlayer anions. As a result, well-crystallized EG intercalated LDH can be synthesized under 550 W microwave irradiation at 120 ℃ for 10 min. The EG intercalated LDH prepared shows similar structure and properties and higher crystallinity as that prepared by conventional method, while the preparation time can be significantly reduced from 12 h to 10 min.