Precision Construction Of New Solid Acid And Alloy Catalysts And Their Application In Efficient Conversion Of Heavy Carbon Resource

Carbon neutralization is a comprehensive goal,involving all sectors of the national economy and the whole process of social reproduction.The effective and highvalue utilization of heavy carbon resources is one of the paths of carbon emission reduction.At the same time,it has the synergistic effect of pollutant emission reduction,and is undoubtedly an important way to achieve carbon peak and carbon neutralization.At present,the research focus on carbon emission reduction is mainly focused on the energy field,while the research on carbon emission reduction in the industry of efficient and high value utilization of heavy carbon resources needs to be strengthened,especially the efficient and highvalue utilization of inferior coal resources（lignite）with serious air pollution and extremely low thermal efficiency value and the only renewable carbon resources（biomass）has become an important way to achieve carbon peak and carbon targets.Lignite and lignin with low utilization rate is very challenging to selectively stabilize into monocyclic aromatic compounds（MCACs）due to their chemical inertness and geometric complexity.In this paper,magnetic mesoporous polymerization ionic liquid catalyst with mesoporous structure and large specific surface area and alloy catalyst with selective hyperactivation/protection strategy were designed and synthesized,and heavy carbon resource based MCACs were efficiently prepared.Compared with homogeneous catalyst,recycling efficiency was greatly improved.Specific catalyst types and catalyst application achielvements are as follows:（1）We carefully prepared P（4[DVB]-[DSPEAC-2FeCl₃]）with good mesoporous channels,strong Br（?）nsted-Lewis acid sites and hydrophobicity through the mediation of vinyl modified Fe₃O₄ nanoparticles-mediation.Then,we have developed an ultra-efficient strategy for lignite valorization into MCACs via the precise cleavage of interunit C–O bridged bonds over P（4[DVB]-[DSPEAC-2FeCl₃]）.In above-mentioned lignite valorization process,the special mesoporous confinement strengthens the adsorption amount of H₂ and increases the concentration of substrates.Along with Lewis acidic species for the loosening of H–H bond in H₂ and then Br（?）nsted acidic sites for the loosened H–H bond heterolysis to form the immobile H^–and mobile H⁺,and finally the resulting mobile H⁺for the cleavage of C–O bridged bonds,the desired reactivity towards lignite valorization to MCACs is achieved.In addition,P（4[DVB]-[DSPEAC-2FeCl₃]）features hydrophobicity,which efficiently prevents the deactivation and leaching of Br（?）nsted-Lewis acidic sites.The characterization methods further confirm that the high activity of P（4[DVB]-[DSPEAC-2FeCl₃]）in lignite directional valorization into MCACs is ascribed to the synergistic catalysis of strong Br（?）nsted-Lewis acidic sites,mesoporous confinement,and hydrophobic microenvironment.More importantly,P（4[DVB]-[DSPEAC-2FeCl₃]）could be simply recycled by external magnetic fields,offering sustainable and cleaner process for the production of lignite-based MCACs.In light of the high catalytic valorization efficiency and the simplicity of magnetic separation,P（4[DVB]-[DSPEAC-2FeCl₃]）can combine the advantages of functionalized ILs and magnetic multiphase catalysts and opens new avenues for the preparation of novel solid acid catalysts,especially for upgrading heavy carbon resources to MCACs.（2）In order to further explore the role of the hydrophobicity of the polyionic liquid catalyst in the efficient catalytic conversion of lignin,the P（2[CL-C6]-[ILs-2FeCl₃]）with different hydrophobic chain length crosslinkers was accurately constructed.In order to confirm the effect of specific hydrophobicity on lignin catalytic hydrogenation,the water contact angle（WCA）was measured.WCA results confirmed that the high catalytic performance of P（2[CL-C6]-[ILs-2FeCl₃]）in the directional catalytic conversion of lignin to MCACs was closely related to the changes in the hydrophobic microenvironment of polyionic liquids.When the hydrophobic chain length is 6 carbon,the channel has a rich hydrophobic block to provide a suitable hydrophobic microenvironment,which protects the leaching and deactivation of the active sites of Br（?）nsted-Lewis acid,and this catalyst retains a large S_BET value.The here reported synergistic catalytic system converting aromatic lignin into value-added MCACs adds new options in lignin efficient utilization offering possible solutions to two key challenges,namely,the accumulation of highly persistent aromatic lignin in the environment and the excessive dependence on fossil fuels for the production of MCACs and their downstream chemicals.（3）The efficient directional conversion of lignin into monomeric phenols without destroying their aromatic structures under hydrogen-rich environment is extremely challenging.Herein,Ni-Cu/Fe₃O₄@Nb₂O₅ featuring Ni-Cu alloy nanoparticles and affluent oxygen vacancieswas successfully fabricated by a concise and highyielding co-deposition/thermal treatment approach.This alloy catalyst exhibits 84.51%conversion of alkaline lignin with 57.82 wt.%yield of monomeric phenols,which is an exceptional and unprecedented results.Systematic experimental investigation together with density functional theory calculation further suggests that the ultra-selective hydro-valorization of lignin into monomeric phenols can be easily achieved through a selective hyper-activation/protection strategy triggered by intra-alloy electron transfer for the first time.Moreover,the confinement effect of oxygen vacancy on active-hydrogen diffusion and C_ar–OC_alk bonds adsorption/activation also play a crucial role in the directional harvest of lignin-based monomeric phenols.This study opens a new direction towards achieving the ultra-selective hydrocracking of heavy carbon resources into monomeric phenols.