Polymeric carbon material from waste sulfuric acid of alkylation and its application in biodiesel production

The huge waste sulfuric acid from isobutane/butene alkylation, which contains acid soluble oil and can lead environment pollution and waste of resources, is difficult to deal with. For the treatment of alkylation waste sulfuric acid, the process convert waste sulfuric acid into dilute sulfuric acid and polymerized carbon materials through direct polymerization of acid soluble oil at below 473.15 K is proposed. Compared with the traditional pyrolysis process at 1373.15 K, the technology developed in this study can save more energy efficient with reduced carbon emissions. It was found that the removal rate of organic matter in waste acid was higher than 99.5 wt % at 453.15K. The dilute sulfuric acid obtained from the reaction can be used in the synthesis of sulphate. The polymeric carbon material has strong acidity. Further study indicates that the polymeric carbon material can be used as an efficient solid acid catalyst for the esterification of oleic acid and methanol to produce biodiesel. The results showed that conversion of oleic acid could reach 95.03 wt % under the optimized conditions, which remained higher than 91 wt % after reuse for 5 times. This work provides an alternative method to treat waste sulfuric acid and also a feasible and low cost route to obtain polymeric carbon material from the organic resources in the sulfuric acid as solid acid catalyst, which can reduce the manufacturing cost of biodiesel.