Preparation Of Graphene-based Catalysts And Their Application In Catalytic Conversion Of Terpenes

Turpentine is not only the important renewable resource,but also precious industrial chemicals.?-Pinene and ?-Pinene are the main components of turpentine,which special chemical structure make its chemically active enough to take part in many reaction,such as isomerization,hydrogenation and oxidation reaction.Turpentine can be used in a variety of chemical synthesis industry,mainly for the synthesis of chemical intermediates,camphor,borneol,spices and rubber.Turpentine is natural,renewable,we can take advantage of their unique reactivity to develop green products.Graphene is a new carbon material,has been widespread concernd in the catalytic system.Its unique physical,chemical and mechanical properties are outstanding,and could allow the preparation of composite-materials with unprecedented characteristics.Doping can impart graphene unique properties,while the load graphene nanoparticles can be effectively reduced ?-? effect between the graphene sheets,thus avoiding the stacked layers of graphene sheets,which contributes to the preparation of highly dispersed composite material.Synergistic coupling between the nanoparticles and rGO possiblely improve the catalytic activity of the composite material.Meanwhile,the graphene oxide surface is rich in oxygen-containing functional groups,such as carboxyl,hydroxyl,epoxy groups.By using these oxygen-containing group,graphene oxide surface could be modified to obtain a composite material.By modificating organic or inorganic molecules onto graphene oxide can make graphene oxide diversified nature of the original single,it enriched its prospects,which makes graphene-based materials become an excellent carrier material.Therefore,it has been recognized as an ideal candidate for supporting various transition metal complexes.The main research contents as follows:(1)The Ni-B/rGO amorphous composite catalysts were prepared by one step chemical reduction with NaBH4 as reducing agent,and tested with the catalytic hydrogenation of pinene as the probing reaction.The results have shown that the as-made catalysts exhibited high catalytic activity and higher enantioselectivity for cis-Pinane of 96.5%,which is better than the traditional Reney nickel and other nickel-based catalysts.The catalyst has good stability,evidenced by the fact that after being cycled 8 times,both the conversion of pinene and the enantioselectivity to cis-Pinane remain at a good level.The structure and properties of the composite catalytic materials were examined by XRD,XPS,TEM techniques,and the relationship between the catalytic performance and the structure of Ni-B/rGO amorphous catalyst was explored.The higher activity of the Ni-B/rGO amorphous catalyst could be attributed to the higher dispersion of the Ni-B active speci.es with unique electronic structure and the interaction between the Ni-B active species and the rGO in the composite catalysts.(2)Graphite oxides were prepared from graphite by the Hummers method and that was used to immobilize Salen Mn complex.To provide the Salen ligands,GO was covalently modified with an aminosilane,followed by condensation with salicylaldehyde.The structure and properties of the composite catalytic materials were examined by FT-IR,XRD,XPS,TEM,TG techniques,and the relationship between the catalytic performance and the structure of Salen Mn-GO catalyst was explored.The immobil'ized Salen Mn complex kept the two-dimensional sheet like GO and showed highly effective for epoxidation of a-Pinene under low concentrations of hydrogen peroxide.The catalyst has good stability,evidenced by the fact after,being cycled 5 times,both the conversion of pinene and the selectivity to 2,3-epoxypinane remained at a good level.