Preparations And Applications Of Industrial Lignin-derived Ordered Mesoporous Carbons And Its Corresponding Solid Acids

In this paper,two types of industrial lignin-derived ordered mesoporous carbons（LDMC_E and LDMC_S）were prepared using masson pine alkali lignin as carbon source by the methods of evaporation-induced self-assembly and salt-induced self-assembly,respectively,and applied to the controlled release of captopril（CapH₂）.Subsequently,using the prepared LDMC_E and LDMC_S as catalyst supports,two types of industrial lignin-derived mesoporous carbon solid acids（LDMC_E-SO₃H and LDMC_S-SO₃H）were obtained by subsequent sulfonation treatment,and applied to the hydrolysis of microcrystalline cellulose（MCC）to glucose.The effects of triblock copolymer（F127）dosage,carbonization temperature and 1,2,4-trimethylbenzene（pore-enlarging agent）dosage on the mesoporous structure of industrial lignin-derived ordered mesoporous carbon were investigated.The optimized LDMC_E possessed well-ordered 2D hexagonal mesoporous characteristics with specific surface area of 345.4 m²/g,mesopore volume of 0.025 cm³/g and meospore size of 3.4 nm under the conditions of molar ratio of F127 to phenol of 0.015,carbonization temperature of 900 °C and mass ratio of pore-enlarging agent to F127 of 0.6.And the optimized LDMC_S possessed worm-like mesoporous characteristics with specific surface area of 598.4 m²/g and mesopore volume of 0.135 cm³/g as well as meospore size of 3.4 nm under the conditions of molar ratio of F127 to phenol of 0.013 and carbonization temperature of 900 °C.The as-prepared LDMC_E and LDMC_S were used as drug carriers and applied to the controlled release of CapH₂.As a result,it was found that there were obvious differences in the load capacity and the processes of CapH₂adsorption and release.Adsorption kinetics studies indicated that the CapH₂ adsorption on LDMC_E was a liquid film diffusion-cotrolling process with more following Weber-Morris kinetic model,but the CapH₂ adsorption on LDMC_S was an intraparticle diffusion-cotrolling process with more following Weber-Morris kinetic model and Bangham kinetic model.Moreover,it was found that Higuchi kinetic model could better describe the release processes of CapH₂on LDMC_E and LDMC_S,indicating the intraparticle diffusion-controlling release processes.Both CapH₂/LDMC_E and CapH₂/LDMC_S showed suitable controlled-release characteristics,but the latter sustained-release effect was better.LDMC_E-SO₃H and LDMC_S-SO₃H prepared by sulfonation treatment contained the high density of-SO₃H groups（1.82 mmol/g and 2.04 mmol/g）,and still maintain the original morphology of the channels,but the specific surface area and mesopore volume showed different degrees of reduction.LDMC_E-SO₃H and LDMC_S-SO₃H were used as catalysts to optimize the process of MCC hydrolysis to glucose.A glucose yield of 48.99% was obtained using LDMC_E-SO₃H as the catalyst under the optimal conditions of reaction temperature and time of 200 °C and 2 h,initial MCC concentration of 7 mg/mL and catalyst load of 3 mg/mg.And a glucose yield of 54.42% was obtained using LDMC_S-SO₃H as the catalyst under the optimal conditions of reaction temperature and time of 190 °C and 3 h,initial MCC concentration of 4 mg/mL and catalyst load of 3 mg/mg.After five runs of LDMC_E-SO₃H and LDMC_S-SO₃H,the glucose yields decreased to 28.85% and 30.35%,respectively,and could be recovered to 39.02% and 45.98% after resulfonation.In summary,the prepared LDMC_S-SO₃H has more excellent catalytic activity than LDMC_E-SO₃H under the corresponding optimal reaction conditions.This research provides a new path for high-value utilization of lignin and green synthesis of mesoporous carbon solid acid,which can effectively hydrolyze cellulose to glucose and partially alleviate the plight of resource shortage.