Hierarchical Flower-Like NiCu/SiO₂ Bimetallic Catalysts with Enhanced Catalytic Activity and Stability for Petroleum Resin Hydrogenation

Abstract

The catalytic hydrogenation of petroleum resin (PR) is an efficient process to produce high-value-added hydrogenated PR with improved performance and wide applications. Herein, a hierarchical flower-like NiCu/SiO 2 bimetallic catalyst has been successfully prepared by reducing the hierarchically structured NiCu silicate precursor ((Ni,Cu) 3 Si 2 O 5 (OH) 4 ) and applied for PR hydrogenation. The generated bimetallic NiCu alloy nanoparticles are anchored on the surface of the intercrossed silica nanoplatelets, constructing a unique multilevel NiCu/SiO 2 superstructure. Moreover, the addition of Cu could not only lower the reduction temperature of Ni species but also provide electrons to Ni to form electron-rich active sites. The NiCu/SiO 2 bimetallic catalyst exhibited enhanced catalytic activity and stability for PR hydrogenation. The hydrogenation degrees for C 5 PR and C 9 PR could reach up to 94.9 and 96.3%, respectively, which are much higher than those catalyzed by the catalyst prepared via an impregnation method (85.9 and 88.7%). Such notably enhanced performances could be ascribed to the synergistic effect between Ni−Cu bimetals and the highly porous superstructure. Our findings provide guidance for the design and synthesis of efficient and stable bimetallic nanocatalysts for PR hydrogenation.

Understanding the Role of Coordinatively Unsaturated Al3+ Sites on Nanoshaped Al2O3 for Creating Uniform Ni–Cu Alloys for Selective Hydrogenation of Acetylene

“…852–853 eV and the 2p 1/2 at 869–970 eV. For the Ni–Cu/sh-Al 2 O 3 sample, these peaks appear at 852.7 and 869.9 eV with the binding energy (BE) typical of a Ni 0 species . The equivalent peaks for the spindle and rod samples shift to lower BE suggesting a degree of electron transfer from Cu to Ni .…”

“…For the Ni−Cu/sh-Al 2 O 3 sample, these peaks appear at 852.7 and 869.9 eV with the binding energy (BE) typical of a Ni 0 species. 44 The equivalent peaks for the spindle and rod samples shift to lower BE suggesting a degree of electron transfer from Cu to Ni. 45 Furthermore, the extent of this shift seems to correlate with the alloying degree (i.e., Ni−Cu/r-Al 2 O 3 has the lowest BE (852.2 eV) but is the most ordered alloy).…”

High-Temperature Stability and Pyrolysis Kinetics and Mechanism of Bio-Based and Petro-Based Resins Using TG–FTIR/MS

“…Thermoplastic resins are widely applied in adhesives, hot melts, printing inks, coatings, varnishes, rubber tires, sealants, and floor tiles due to their excellent weatherability, light aging resistance, high-temperature stability, adhesiveness, and miscibility. − The C9 petro-based resin (C9PR), which is typically synthesized by the polymerization of C9 fraction (such as indene, methylstyrene, α-methylstyrene, dicyclopentadiene, and so on) derived from ethylene cracking in the petroleum industry, is one of the most important petro-based thermoplastic resins and possesses good high-temperature stability and high mechanical properties due to the high cycloaliphatic or aromatic content. − The hydrogenated C9 petro-based resin (HC9PR) with high oxidation stability and light color is obtained by hydrogenation of C9PR and shows a higher application value than C9PR, which is due to the fact that the C9PR is rich in unsaturated bonds, especially ethylenic CC bonds, and easily oxidized in air, resulting in a darker color, poor oxidation stability, poor adhesiveness, and poor compatibility. − Despite having good properties, C9PR and HC9PR are banned for application in food and pharmaceutical additives owing to hazards to human health, such as strong carcinogenic naphthalene and indene. , In addition, the continuous use of petro-based resins may result in large consumption of petrochemical resources. Since the commercialization of petro-based products in 1950, their production has increased steadily and now accounts for about 800 ktons of the annual world production. , Considering the energy and health problems caused by petro-based thermoplastic resins, there is a requirement to develop environmentally friendly and renewable biological resources for the synthesis of bio-based thermoplastic resins.…”

“…Rosin glyceride (RGE) and hydrogenated rosin glyceride (HRGE) have become promising alternatives to petro-based resins due to their renewable, environmentally friendly, nontoxic, and good compatibility properties and are widely used in chewing gum base, plasters, drug film coatings, etc. − RGE and HRGE are bio-based thermoplastic resins synthesized by the esterification of glycerol with rosin or hydrogenated rosin and have similar rigidity to petro-based resins due to their large tricyclic phenanthrene structure. − Rosin is an abundantly renewable resin that is obtained naturally from exudations of pines and conifers or from the tall oil as a byproduct of paper pulp production and is made up of 90% tricyclic phenanthrene resin acids and 10% neutral compounds. − Similar to C9PR, rosin has conjugated double bonds that are easily oxidized, reducing product quality; thus, hydrogenation modification of rosin or RGE is carried out, and then, HRGE with light color and high oxidation stability is synthesized. ,, About 1000 ktons of raw rosin is produced each year, of which 250 ktons of chewing gum base (mainly rosin esters) is produced worldwide every year. ,, As a result, it is important to assess the substitution or blending potential of bio-based and petro-based resins. Typically, adhesiveness, compatibility, color, oxidation stability, and high-temperature stability are important characteristics for industrial applications of bio-based and petro-based resins. ,,,− In terms of compatible and adhesive properties, the application of RGE or HRGE as a substitute for petro-based resins has been reported, such as hot melt adhesives , and pressure-sensitive adhesives. , Besides, based on the color and antioxidant properties, many researchers have focused on the hydrogenation of bio-based and petro-based resins. − , Although some studies concerning the high-temperature stability and pyrolysis kinetics of rosin or dicyclopentadiene resins have been carried out, , the study on the high-temperature stability comparison between bio-based and petro-based resins is still lacking. In addition, to the best of our knowledge, no information on the pyrolysis kinetics and mechanism of RGE, HRGE, C9PR, and HC9PR is available in the open literature.…”

“…22,26 Besides, based on the color and antioxidant properties, many researchers have focused on the hydrogenation of bio-based and petro-based resins. [9][10][11]27 Although some studies concerning the high-temperature stability and pyrolysis kinetics of rosin or dicyclopentadiene resins have been carried out, 23,24 the study on the hightemperature stability comparison between bio-based and petrobased resins is still lacking. In addition, to the best of our knowledge, no information on the pyrolysis kinetics and mechanism of RGE, HRGE, C9PR, and HC9PR is available in the open literature.…”