Formaldehyde(HCHO)is a significant indoor pollutant found in various sources and poses potential health risks to humans.Noble metal catalysts show efficient and stable catalytic activity for ambient-temperature HCHO o...Formaldehyde(HCHO)is a significant indoor pollutant found in various sources and poses potential health risks to humans.Noble metal catalysts show efficient and stable catalytic activity for ambient-temperature HCHO oxidation,yet suffer from low metal utilization.Efforts focus on designing catalysts with enhanced intrinsic activity and reduced noble metal loading.In this study,we developed a simple pretreatment method using ammonia solution on SiO_(2)carrier to enhance the activity of the Pd/SiO_(2)catalyst for HCHO oxidation.After the carrier was pretreated with an ammonia solution,a significant promoting effect was observed on the Pd/SiO_(2)(NH_(3)·H_(2)O)-R catalyst.It achieved almost complete oxidation of 150 ppmV of HCHO at 25℃,much better than the Pd/SiO_(2)-R(5%HCHO conversion rate).Multiple characterization results indicated that the ammonia solution pretreatment of the SiO_(2)carrier increased the surface defects,facilitating the anchoring of Pd nanoparticles and increasing their dispersion.The increase dispersion of Pd resulted in the generation of additional oxygen vacancies on the catalyst surfaces.The increased in oxygen vacancies on the catalyst was beneficial for enhancing the catalyst's ability to activate H_(2)O to form surface hydroxyl groups,thereby accelerating the catalytic oxidation process of HCHO.The reaction mechanism of HCHO on the Pd/SiO_(2)(NH_(3)·H_(2)O)-R catalyst mainly follows an efficient pathway:firstly,the HCHO being oxidized by surface active hydroxyl groups to formate;subsequently,the formate being oxidized by hydroxyl groups to H_(2)O and CO_(2).This study provides a promising strategy for designing high-performance noble metal catalysts for HCHO catalytic oxidation.展开更多
Highly dispersed noble metals are acknowledged for its pivotal role in influencing the efficiency of catalysts during the HCHO oxidation process.Interestingly,in this work,an innovative approach was employed to augmen...Highly dispersed noble metals are acknowledged for its pivotal role in influencing the efficiency of catalysts during the HCHO oxidation process.Interestingly,in this work,an innovative approach was employed to augmenting the stabilization of noble metals on irreducible carriers supported noble metal catalyst(Pd/SiO_(2))by adding alkali metal potassium(K).A formidable promotion effect was observed when the K doping to Pd/SiO_(2) catalysts.It achieves a conversion rate of 93%for 270 ppmV of HCHO to harmless CO_(2) and H_(2)O at a weight hourly space velocity(WHSV)of 300,000 mL/(g·hr)at 25℃.Multiple characterization results illustrated that a strong interaction between added K and Pd species was formed after K addition,which not only stabilized Pd species on the carrier surface but alsomarkedly enhanced its dispersal on the SiO_(2) carrier.The increasing Pd dispersion induced more oxygen vacancies on the surfaces of the Pd/SiO_(2) catalysts.The formation of these oxygen vacancies can be attributed to the phenomenon of hydrogen spillover,which also contributed to elevating the electron density on the Pd sites.Meanwhile,the oxygen vacancies favored the O_(2) activation to formmore reactive oxygen species participating in the HCHO oxidation reaction,thus improving the performance of Pd/SiO_(2) catalysts displayed for HCHO oxidation.This study provides a simple strategy to design high-performance irreducible carriers supported noble metal catalysts for HCHO catalytic oxidation.展开更多
基金supported by the Sanming University(No.23YG05)the Science Foundation of Fujian Province(No.2023J011027).
文摘Formaldehyde(HCHO)is a significant indoor pollutant found in various sources and poses potential health risks to humans.Noble metal catalysts show efficient and stable catalytic activity for ambient-temperature HCHO oxidation,yet suffer from low metal utilization.Efforts focus on designing catalysts with enhanced intrinsic activity and reduced noble metal loading.In this study,we developed a simple pretreatment method using ammonia solution on SiO_(2)carrier to enhance the activity of the Pd/SiO_(2)catalyst for HCHO oxidation.After the carrier was pretreated with an ammonia solution,a significant promoting effect was observed on the Pd/SiO_(2)(NH_(3)·H_(2)O)-R catalyst.It achieved almost complete oxidation of 150 ppmV of HCHO at 25℃,much better than the Pd/SiO_(2)-R(5%HCHO conversion rate).Multiple characterization results indicated that the ammonia solution pretreatment of the SiO_(2)carrier increased the surface defects,facilitating the anchoring of Pd nanoparticles and increasing their dispersion.The increase dispersion of Pd resulted in the generation of additional oxygen vacancies on the catalyst surfaces.The increased in oxygen vacancies on the catalyst was beneficial for enhancing the catalyst's ability to activate H_(2)O to form surface hydroxyl groups,thereby accelerating the catalytic oxidation process of HCHO.The reaction mechanism of HCHO on the Pd/SiO_(2)(NH_(3)·H_(2)O)-R catalyst mainly follows an efficient pathway:firstly,the HCHO being oxidized by surface active hydroxyl groups to formate;subsequently,the formate being oxidized by hydroxyl groups to H_(2)O and CO_(2).This study provides a promising strategy for designing high-performance noble metal catalysts for HCHO catalytic oxidation.
基金supported by the Youth Innovation Promotion Association,CAS(No.2020310)Sanming University(No.23YG05).
文摘Highly dispersed noble metals are acknowledged for its pivotal role in influencing the efficiency of catalysts during the HCHO oxidation process.Interestingly,in this work,an innovative approach was employed to augmenting the stabilization of noble metals on irreducible carriers supported noble metal catalyst(Pd/SiO_(2))by adding alkali metal potassium(K).A formidable promotion effect was observed when the K doping to Pd/SiO_(2) catalysts.It achieves a conversion rate of 93%for 270 ppmV of HCHO to harmless CO_(2) and H_(2)O at a weight hourly space velocity(WHSV)of 300,000 mL/(g·hr)at 25℃.Multiple characterization results illustrated that a strong interaction between added K and Pd species was formed after K addition,which not only stabilized Pd species on the carrier surface but alsomarkedly enhanced its dispersal on the SiO_(2) carrier.The increasing Pd dispersion induced more oxygen vacancies on the surfaces of the Pd/SiO_(2) catalysts.The formation of these oxygen vacancies can be attributed to the phenomenon of hydrogen spillover,which also contributed to elevating the electron density on the Pd sites.Meanwhile,the oxygen vacancies favored the O_(2) activation to formmore reactive oxygen species participating in the HCHO oxidation reaction,thus improving the performance of Pd/SiO_(2) catalysts displayed for HCHO oxidation.This study provides a simple strategy to design high-performance irreducible carriers supported noble metal catalysts for HCHO catalytic oxidation.
