餐饮废油一步制备炭基固体酸及用于催化油酸合成生物柴油的研究

Preparation of carbon-based solid acid catalyst from waste cooking oil and its catalytic application in biodiesel production via esterification of oleic acid

以餐饮废油为碳源,浓硫酸为磺化剂,在管式电阻炉中一步炭化和磺化制备得到一种新的炭基固体酸催化剂,并对制备的固体酸催化剂进行理化性能表征。将制备的固体酸催化剂用于催化油酸与甲醇酯化反应合成生物柴油。考查了废油炭化温度对固体催化剂活性的影响。结果表明,在餐饮废油/浓硫酸质量比为0.25、温度为220℃、N_2流量为80 cm^3/min、时间30 min时,制备的固体酸催化剂活性最高。此外,考查了酯化反应条件对油酸转化率的影响,结果表明,当反应时间为10 h、反应温度为80℃、甲醇油酸摩尔比为10∶1、催化剂质量为油酸质量的10.0%时,油酸最大转化率为95.8%。当催化剂循环利用第3次时,油酸转化率仍达到69.1%。

A new carbon-based solid acid catalyst is prepared through one-step carbonization and sulfonation in a tubular furnace with waste cooking oil as raw materials and H2SO4as sulfonating agent.Physicochemical properties of the obtained catalyst are characterized.The catalyst is employed to catalyze the esterification reaction between oleic acid and methanol to synthesize biodiesel.Influences of carbonization temperature for waste cooking oil on the activity of solid catalyst are investigated.Results indicate that the optimal preparation conditions for catalyst are as follows:the mass ratio of waste cooking oil to sulfuric acid is equal to 1∶4,carbonization temperature is at 220℃,N2flow rate is 80 cm3·min-1and carbonization lasts for 30 min.In addition,the effects of esterification conditions on the conversion rate of oleic acid are investigated.It is found that a maximum oleic acid conversion of 95.8%is obtained under the optimal conditions such as reaction time for 10 h,80℃,methanol to oleic acid molar ratio at 10∶1 and 10.0 wt%for catalyst content in oleic acid.The conversion rate oleic acid can still reach 69.1%over the solid acid catalyst that has been used twice.