Mwcnt, Activated Carbon and Al2o3 Supported Palladium Nanocatalysts Synthesi̇s, Characterization and Investigation of the Catalytic Performance in the Reduction of Cr+6 To Cr+3'
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2020
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Hexavalent krom (Cr(VI)) akut toksik, mutajen ve kanserojen olarak tanımlanırken, aksine trivalent krom (Cr(III)) eser miktarlarda canlılar için önemli bir element olduğu düşünülmektedir. Bu çalışmada, çok duvarlı karbon nanotüp (MWCNT), alüminyum oksit (Al2O3) ve aktif karbon (C) üzerinde desteklenen paladyum(0) nanokatalizörleri (Pd(0)@MWCNT, Pd(0)@Al2O3, Pd(0)@C) ılımlı koşullar altında emdirme-indirgenme tekniği ile tekrar kullanılabilir şekilde sentezlendi ve HR-TEM, TEM-EDX, DR/UV-vis, P-XRD, ICP-OES ve XPS teknikleri ile karakterize edildi. Sonuçlar MWCNT, Al2O3 ve C destek malzemelerinin yüzeyinde iyi dağılmış paladyum(0) nanopartiküllerinin (2.20 ± 0.25 nm, 3.01 ± 0.19 nm, 3.98 ± 0.24 nm) oluşumuna işaret etmektedir. Ortaya çıkan paladyum(0) nanokatalizörlerinin aktivite ve kararlılık bakımından katalitik performansları, indirgeyici ajan olarak formik asit (HCOOH) varlığında, Cr(VI)'nın katalitik indirgenmesinde incelenmiştir. Nanokatalizörlerinin yüksek seçicilik (~ % 100) ve yüksek aktivite (TOF) (Pd(0)@MWCNT, Pd(0)@Al2O3, Pd(0)@C için sırayla; 286, 138, 31 mol Cr2O7-2/mol Pd dk.) ile Cr(VI)'nın Cr(III)'e indirgenmesini etkili bir şekilde katalize ettiği bulunmuştur. Katalizörler [Pd(0)@MWCNT, Pd(0)@Al2O3, Pd@C], sübstrat [Cr2O7-2], formik asit [HCOOH], sodyum format [HCOONa] konsantrasyonları ve sıcaklık parametrelerine ait katalitik reaksiyonun doğasını anlamak amacıyla, hız ifadesi ve aktivasyon parametreleri (Ea, ΔH# ve ΔS#) belirlenmiştir.
Hexavalent chrome (Cr(VI)) is defined as acutely toxic, mutagenic and carcinogenic, whereas trivalent chrome (Cr(III)) is thought to be an important element for living creatures in trace amounts. In this study, palladium(0) nanocatalysts (Pd(0)@MWCNT, Pd(0)@Al2O3, Pd(0)@C) supported over multi-walled carbon nanotube (MWCNT), aluminum oxide (Al2O3) and activated carbon (C) were reusably synthesized by the impregnation-reduction technique under mild conditions and characterized by HR-TEM, TEM-EDX, DR/UV-Vis, P-XRD, ICP-OES and XPS techniques. The results indicate the formation of very well dispersed metallic palladium(0) nanoparticles (2.20 ± 0.25 nm, 3.01 ± 0.19 nm, 3.98 ± 0.24 nm) onto the surface of the MWCNT, Al2O3 and C support materials. The stability and activity of catalytic perfomance of the obtained palladium(0) metal nanocatalysts were investigated in the reaction of chrome (VI) to chrome (III) in the existence of formic acid (HCOOH). Nanocatalysts were found to effectively catalyze the reduction of Cr (VI) to Cr (III) with high selectivity (~ 100 %) and high activity (TOF) (for Pd(0)@MWCNT, Pd(0)@Al2O3, Pd(0)@C respectively; 286, 138, 31 mol of Cr2O7-2/mol Pd min). To understand the natural structure of the catalytic reduction reaction of catalysts [Pd(0)@MWCNT, Pd(0)@Al2O3, Pd@C], dichromate substrate [Cr2O72−], formic acid [HCOOH], sodium formate [HCOONa] concentrations and temperature parameters, the velocity statement and activation parameters (ΔH#, ΔS# and Ea) were determined.
Hexavalent chrome (Cr(VI)) is defined as acutely toxic, mutagenic and carcinogenic, whereas trivalent chrome (Cr(III)) is thought to be an important element for living creatures in trace amounts. In this study, palladium(0) nanocatalysts (Pd(0)@MWCNT, Pd(0)@Al2O3, Pd(0)@C) supported over multi-walled carbon nanotube (MWCNT), aluminum oxide (Al2O3) and activated carbon (C) were reusably synthesized by the impregnation-reduction technique under mild conditions and characterized by HR-TEM, TEM-EDX, DR/UV-Vis, P-XRD, ICP-OES and XPS techniques. The results indicate the formation of very well dispersed metallic palladium(0) nanoparticles (2.20 ± 0.25 nm, 3.01 ± 0.19 nm, 3.98 ± 0.24 nm) onto the surface of the MWCNT, Al2O3 and C support materials. The stability and activity of catalytic perfomance of the obtained palladium(0) metal nanocatalysts were investigated in the reaction of chrome (VI) to chrome (III) in the existence of formic acid (HCOOH). Nanocatalysts were found to effectively catalyze the reduction of Cr (VI) to Cr (III) with high selectivity (~ 100 %) and high activity (TOF) (for Pd(0)@MWCNT, Pd(0)@Al2O3, Pd(0)@C respectively; 286, 138, 31 mol of Cr2O7-2/mol Pd min). To understand the natural structure of the catalytic reduction reaction of catalysts [Pd(0)@MWCNT, Pd(0)@Al2O3, Pd@C], dichromate substrate [Cr2O72−], formic acid [HCOOH], sodium formate [HCOONa] concentrations and temperature parameters, the velocity statement and activation parameters (ΔH#, ΔS# and Ea) were determined.
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Kimya, Chemistry
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