Application of Metal–Organic Frameworks with Enhanced Brønsted and Lewis Acidity as Catalysts in the Synthesis of Solketal, a Renewable Fuel Additive

Project no. 32652 · Status: Kapanmış (Yayın bekleniyor) · 2024

Summary

<p class="ql-align-justify">Glycerol&nbsp;is&nbsp;a&nbsp;polyalcohol&nbsp;with&nbsp;three&nbsp;reactive&nbsp;hydroxyl&nbsp;groups&nbsp;that&nbsp;is&nbsp;formed&nbsp;as&nbsp;a&nbsp;byproduct&nbsp;in&nbsp;biodiesel&nbsp;production.&nbsp;It&nbsp;accounts&nbsp;for&nbsp;approximately&nbsp;10%&nbsp;by&nbsp;weight&nbsp;of&nbsp;the&nbsp;biodiesel&nbsp;yield.&nbsp;Therefore,&nbsp;utilizing&nbsp;the&nbsp;released&nbsp;glycerol&nbsp;and&nbsp;converting&nbsp;it&nbsp;into&nbsp;valuable&nbsp;chemicals&nbsp;is&nbsp;considered&nbsp;a&nbsp;crucial&nbsp;step&nbsp;in&nbsp;terms&nbsp;of&nbsp;the&nbsp;success&nbsp;of&nbsp;the&nbsp;biodiesel&nbsp;production&nbsp;process.&nbsp;Since&nbsp;glycerol&nbsp;is&nbsp;a&nbsp;platform&nbsp;chemical,&nbsp;it&nbsp;serves&nbsp;as&nbsp;an&nbsp;important&nbsp;raw&nbsp;material&nbsp;for&nbsp;many&nbsp;products.&nbsp;Among&nbsp;these&nbsp;products,&nbsp;solketal,&nbsp;used&nbsp;as&nbsp;a&nbsp;fuel&nbsp;additive&nbsp;and&nbsp;green&nbsp;solvent,&nbsp;is&nbsp;obtained&nbsp;from&nbsp;the&nbsp;reaction&nbsp;of&nbsp;glycerol&nbsp;with&nbsp;acetone&nbsp;over&nbsp;an&nbsp;acid&nbsp;catalyst.&nbsp;This&nbsp;project&nbsp;aims&nbsp;to&nbsp;synthesize&nbsp;and&nbsp;test&nbsp;a&nbsp;suitable&nbsp;solid&nbsp;catalyst,&nbsp;a&nbsp;valuable&nbsp;step&nbsp;in&nbsp;solketal&nbsp;production.&nbsp;Within&nbsp;the&nbsp;scope&nbsp;of&nbsp;this&nbsp;project,&nbsp;zirconium-based&nbsp;metal-organic&nbsp;framework&nbsp;(MOF)&nbsp;structures&nbsp;with&nbsp;high&nbsp;stability&nbsp;were&nbsp;evaluated.&nbsp;MOFs&nbsp;offer&nbsp;significant&nbsp;advantages&nbsp;in&nbsp;their&nbsp;use&nbsp;as&nbsp;solid&nbsp;catalysts&nbsp;due&nbsp;to&nbsp;their&nbsp;adjustable&nbsp;pore&nbsp;diameter,&nbsp;tunability,&nbsp;and&nbsp;surface&nbsp;morphology.&nbsp;Within&nbsp;the&nbsp;scope&nbsp;of&nbsp;the&nbsp;project,&nbsp;the&nbsp;advantages&nbsp;offered&nbsp;by&nbsp;MOF&nbsp;structures&nbsp;were&nbsp;utilized&nbsp;to&nbsp;synthesize&nbsp;UiO-66,&nbsp;UiO66(FA),&nbsp;DES@UiO-66,&nbsp;Sn@UiO-66,&nbsp;MOF-808,&nbsp;and&nbsp;Sn@MOF-808&nbsp;catalysts.&nbsp;FTIR,&nbsp;SEM,&nbsp;EDS,&nbsp;XRD,&nbsp;TGA,&nbsp;N<sub>2</sub>&nbsp;adsorption-desorption,&nbsp;and&nbsp;butylamine&nbsp;titration&nbsp;analyses&nbsp;were&nbsp;performed&nbsp;to&nbsp;determine&nbsp;the&nbsp;crystal&nbsp;structure,&nbsp;morphology,&nbsp;porosity,&nbsp;surface&nbsp;chemical&nbsp;groups,&nbsp;and&nbsp;thermal&nbsp;behavior&nbsp;to&nbsp;characterize&nbsp;the&nbsp;catalysts.&nbsp;Based&nbsp;on&nbsp;the&nbsp;results,&nbsp;typical&nbsp;crystal&nbsp;structures&nbsp;were&nbsp;observed&nbsp;in&nbsp;the&nbsp;catalysts.&nbsp;Decreases&nbsp;in&nbsp;the&nbsp;intensity&nbsp;of&nbsp;crystal&nbsp;peaks&nbsp;were&nbsp;observed&nbsp;as&nbsp;a&nbsp;result&nbsp;of&nbsp;defects&nbsp;and&nbsp;modifications,&nbsp;and&nbsp;similarly,&nbsp;it&nbsp;was&nbsp;understood&nbsp;that&nbsp;the&nbsp;pore&nbsp;volume&nbsp;decreased&nbsp;as&nbsp;a&nbsp;result&nbsp;of&nbsp;modification,&nbsp;but&nbsp;increased&nbsp;in&nbsp;the&nbsp;defective&nbsp;structure.&nbsp;The&nbsp;presence&nbsp;of&nbsp;micropores&nbsp;and&nbsp;mesopores&nbsp;in&nbsp;the&nbsp;catalyst&nbsp;structures&nbsp;and&nbsp;an&nbsp;increase&nbsp;in&nbsp;the&nbsp;acid&nbsp;strength&nbsp;of&nbsp;the&nbsp;catalysts&nbsp;after&nbsp;modification&nbsp;were&nbsp;observed.&nbsp;The&nbsp;synthesized&nbsp;catalysts&nbsp;were&nbsp;tested&nbsp;in&nbsp;solketal&nbsp;production.&nbsp;According&nbsp;to&nbsp;the&nbsp;reaction&nbsp;results&nbsp;obtained,&nbsp;at&nbsp;a&nbsp;reaction&nbsp;time&nbsp;of&nbsp;60&nbsp;minutes,&nbsp;with&nbsp;a&nbsp;catalyst&nbsp;amount&nbsp;of&nbsp;5%&nbsp;glycerol&nbsp;by&nbsp;weight&nbsp;and&nbsp;an&nbsp;acetone/glycerol&nbsp;molar&nbsp;ratio&nbsp;of&nbsp;10,&nbsp;DES@UiO-66&nbsp;and&nbsp;Sn@UiO-66&nbsp;catalysts&nbsp;achieved&nbsp;over&nbsp;80%&nbsp;glycerol&nbsp;conversion.&nbsp;Solketal&nbsp;selectivity&nbsp;exceeded&nbsp;97%.&nbsp;Hot&nbsp;filtration&nbsp;and&nbsp;reusability&nbsp;were&nbsp;investigated&nbsp;for&nbsp;DES@UiO-66&nbsp;and&nbsp;Sn@UiO-66&nbsp;catalysts,&nbsp;and&nbsp;after&nbsp;four&nbsp;uses,&nbsp;glycerol&nbsp;conversion&nbsp;rates&nbsp;of&nbsp;70.31%&nbsp;and&nbsp;79.17%&nbsp;were&nbsp;obtained&nbsp;for&nbsp;both&nbsp;catalysts,&nbsp;respectively.&nbsp;When&nbsp;the&nbsp;obtained&nbsp;results&nbsp;are&nbsp;evaluated&nbsp;overall,&nbsp;it&nbsp;is&nbsp;concluded&nbsp;that&nbsp;Sn@UiO-66&nbsp;is&nbsp;suitable&nbsp;for&nbsp;solketal&nbsp;production&nbsp;due&nbsp;to&nbsp;its&nbsp;high&nbsp;glycerol&nbsp;conversion&nbsp;and&nbsp;reusability.</p>

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