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The biorefinery is an important approach for the current needs of energy and chemical building block syntheses. 5-hydroxymethylfurfural (HMF) is considered an important renewable building block for the production of levulinic acid and furan derivatives due to its potential availability from carbohydrates such as glucose and sucrose. In the present study, mesoporous zirconium phosphate catalysts (ZP) have been used for the synthesis of HMF from carbohydrates in aqueous media. ZP prepared hydrothermally using P123 as structure-directing agent, calcined at 500-800℃. HRTEM image reveals the presence of worm like highly monodispersed pores. BET surface area and total acid sites of ZP catalyst decreased with increasing calcination temperatures, and calcination temperatures have strong influences on the catalytic activity of ZP. The ZP catalyst, calcined at 600℃, showed ~86% conversion of glucose with maximum HMF yield (~52%) at 155℃ within 6 h seems to be beneficial for HMF synthesis.
Aromatics, particularly p-xylene (pX), has been considered as an important building block for terephthalic acid synthesis that can be used as monomer for polyester and polyethylene terephthalate. In the present study, the SBA-15 supports calcined at the temperature range of 500-900 °C (denoted as SBA-15(500-900)) were modified with zirconium phosphate (ZrP) and they were used for the production of pX from 2,5-dimethylfuran (DMF) with gaseous ethylene through cycloaddition reaction. The ZrP grafted on SBA-15(500) (ZrP-SBA-15(500)) displayed a maximum 89% DMF conversion with 95% pX selectivity, which was significantly higher than the ZrP on the SBA-15(900). The high catalytic performance for pX production on the ZrP-SBA-15(500) is attributed to the formation of different surface active ZrP species from in-situ reaction of both Zr and P precursors on the different silanol groups on the SBA-15(500) with an enhanced acid sites as well.
<P><B>Abstract</B></P> <P>The positive effects of zirconium phosphate (ZrP)-modified highly ordered mesoporous KIT-6 support for an insignificant aggregation of the supported cobalt nanoparticles (CoZrP/KIT-6) were investigated by CO hydrogenation to hydrocarbons such as Fischer-Tropsch synthesis (FTS) reaction. The roles of the newly formed ZrP phases on the KIT-6 were mainly explained in terms of metal dispersion with its modulated metal-support interaction as well as suppressed coke formations. The mesoporous KIT-6 surfaces modified with partial ZrP nanoparticles at an optimum molar ratio of P/Zr = 0.2 significantly enhanced the catalytic stability with a higher C<SUB>5+</SUB> selectivity through the preferential formations of the spatial confined cobalt nanoparticles in the matrices of the well-dispersed ZrP nanoparticles on the mesoporous KIT-6 surfaces. The superior catalytic activity and stability were mainly attributed to the inhibited aggregations of the intimately interacted cobalt nanoparticles in the ZrP matrices due to a preferential presence of the highly dispersed and thermally stable hydrophobic ZrP phases. This was also responsible for the less formation of coke precursors such as cobalt carbides or heavy wax hydrocarbons. However, the different types of coke precursors on the used CoZrP/KIT-6 largely altered the catalytic stability and activity with the simultaneous aggregations of cobalt nanoparticles by forming the abundant heavy hydrocarbons on the unstable CoZrP(2)/KIT-6 prepared at a higher P/Zr ratio of 2 as well as by forming the inactive coke-derived cobalt carbides on the unmodified CoZrP(0)/KIT-6 and Co/KIT-6 under the reductive FTS reaction condition.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Positive effects of zirconium phosphate (ZrP)-modified KIT-6 were investigated by CO hydrogenation to hydrocarbons. </LI> <LI> Enhanced stability was originated from spatial confined cobalt nanoparticles in the thermally stable ZrP matrices. </LI> <LI> Highly dispersed and thermally stable hydrophobic ZrP phases are responsible for a less coke formation. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>