Paper-like Stainless Steel Fibers Research Articles

Preparation of a new B-CNTs/PSSF composite catalyst for catalytic wet peroxide oxidation of phenol in structured fixed bed

A new structured catalyst consisting of boron-doped carbon nanotubes growing directly on paper-like stainless steel fibers support (B-CNTs/PSSF) was developed for continuous catalytic wet peroxide oxidation (CWPO) of phenol in a structured fixed bed. Firstly, B-CNTs/PSSF was synthesized by chemical vapor deposition (CVD) with phenyboronic acid as a single precursor and CNTs/PSSF was prepared with camphor for comparison. Secondly, the effects of different deposition temperatures, deposition times, and phenylboronic acid dosages on the morphology and properties of B-CNTs were investigated, respectively. The results verified that under the conditions of deposition temperature of 750 °C, deposition time of 20 min, and phenylboronic acid dosage of 2 g, the B-CNTs/PSSF composite catalyst with uniform growth density, wavy and kinked morphology, abundant oxygen-containing functional groups and defect sites, and boron-doped content of 2.96% was successfully prepared. Then, the performance of B-CNTs/PSSF for continuous CWPO of phenol was evaluated. Catalytic results revealed that the B-CNTs/PSSF showed excellent catalytic activity in phenol degradation within 7 h (phenol conversion reached about 100% and total organic carbon (TOC) conversion was up to 68%). In contrast, the average phenol and TOC conversion of CNTs/PSSF were about 75% and 35%, respectively. It indicated that boron doping endowed CNTs with higher catalytic activity.

Preparation and application of Co3O4 catalysts from ZIF-67 membranes over paper-like stainless steel fibers in isopropanol combustion

Co3O4 catalysts supported on paper-like stainless steel fibers (PSSF) were prepared by MOFs-templated (M) method and applied for catalytic combustion of isopropanol. Physicochemical properties of the as-synthesized Co3O4 catalysts were investigated by SEM, EDS mapping, TEM, XRD, BET, XPS and H2-TPR, respectively. Characterization results of SEM and TEM shown that Co3O4 (M)-350 and Co3O4 (M)-400 still remained the dodecahedron shape of the ZIF-67 precursor and possessed porous structures. The XPS results shown that the ratio of Co3+/Co2+ and Oc/Oc ​+ ​Oa ​+ ​Ol firstly increased and then decreased with the increase of calcination temperature. Among the as-synthesized catalysts, Co3O4(M)-400 exhibited the highest activity for the catalytic combustion of isopropanol with the T50 and T90 values of 258 ​°C and 281 ​°C, respectively, which was associated with high BET surface area, high amount of Co3+ species and abundant surface chemisorbed oxygen. Moreover, Co3O4 (M)-400 was employed as a structured catalyst for isopropanol combustion, the catalytic kinetics were studied based on different feed concentration, bed height and GHSV. The experimental results indicated that the T50 and T90 of isopropanol combustion over Co3O4(M)-400 with the bed height of 2 ​cm were increased slightly as the GHSV and feed concentration of isopropanol increased.

High efficient HKUST-1 membrane over paper-like steel fibers for direct catalytic wet peroxide oxidation of phenol

A HKUST-1 metal-organic framework membrane was constructed on the high voidage three-dimensional paper-like stainless steel fibers (PSSF) and was applied for the catalytic wet peroxide oxidation (CWPO) of phenol in a structured fixed bed for the first time. The chemical structure, surface areas, thermal stability of the obtained HKUST-1 membrane/PSSF support were characterized by using SEM, XRD, XPS, TGA and FT-IR. The results indicated that the HKUST-1 membrane/PSSF showed an intact morphology with octahedron crystal and a specific surface area of 376.72 m2 g−1, and it was stable in the air before 320 °C. The effects of the temperature, the catalyst bed height, and the feed flow rate on the catalytic performance of the membrane were investigated by monitoring the conversion of phenol, TOC, H2O2, respectively. Under the optimum condition of 3 cm bed height, 80 °C of catalytic temperature, 2 mL min −1 of the feed flow rate, the conversion of phenol and TOC could reach to 100% and 70%, respectively. The HKUST-1 membrane/PSSF could maintain a phenol conversion of 80% and a TOC conversion of 39% after being used for three times.

Preparation and characterization of Cu and Mn modified beta zeolite membrane catalysts for toluene combustion

Cu and Mn as well as their mixed oxides modified beta zeolite membrane (Beta) coating on paper-like stainless steel fibers (PSSF) catalysts were successfully prepared and applied in toluene combustion. Firstly, Beta/PSSF with different crystallization temperature, crystallization time, Si/Al ratios etc. were prepared using secondary growth method, meanwhile, XRD, SEM and N2 adsorption-desorption isotherms were utilized to analyze the structures of the samples, respectively. Then, Cu and Mn as well as their mixed oxides loaded onto the obtained beta zeolite membrane with the optimal parameter were prepared by impregnating method. Finally, toluene combustion experiment was performed over a fixed-bed reactor. The experimental results depicted that continuous and well-intergrown beta zeolite membrane covered on the PSSF with typical truncated bipyramidal shape, and Beta/PSSF had a three-dimensional network with large void volume and majority of microporous. For the catalysts, the copper element existed as Cu2+ and Cu1+, and manganese element existed as Mn4+, Mn3+, and Mn2+. As a result, the catalytic activities for toluene combustion over mixed oxides as catalysts were superior to the single metal oxide catalysts. The T10, T50 and T90 of toluene combustion were dramatically decreased over Cu-Mn (1:3)- Beta/PSSF.

Preparation and characterization of novel carbon molecular sieve membrane/PSSF composite by pyrolysis method for toluene adsorption

Carbon molecular sieve membrane (CMSM)/paper-like stainless steel fibers (PSSF) has been manufactured by pyrolyzing poly (furfuryl alcohol) (PFA) coated on the metal fibers. PFAwas synthesized using oxalic acid dihydrate as a catalyst and coated on microfibers by dip coating method. For the purpose of investigating the effects of final carbonization temperature, the composites were carbonized between 400°C and 800°C under flowing nitrogen. The morphology and microstructure were examined by X-ray diffraction, Fourier transforms infrared spectroscopy, scanning electron microscopy, thermogravimetric analysis, N2 adsorption and desorption, Raman spectra and X-ray photoelectron spectra. The consequences of characterization showed that the CMSM containing mesopores of 3.9 nm were manufactured. The specific surface area of the CMSM/PSSF fabricated in different pyrolysis temperature varies from 26.5 to 169.1 m2·g-1 and pore volume varies from 0.06 to 0.23 cm3·g-1. When pyrolysis temperature exceeds 600°C, the specific surface, pore diameter and pore volume decreased as carbonization temperature increased. Besides, the degree of graphitization in carbon matrix increased with rising pyrolysis temperature. Toluene adsorption experiments on different structured fixed bed that was padded by CMSM/PSSF and granular activated carbon (GAC) were conducted. For the sake of comparison, adsorption test was also performed on fixed bed packed with GAC. The experimental results indicated that the rate constant κ’ was dramatically increased as the proportion of CMCM/PSSF composites increased on the basis of Yoon-Nelson model, which suggested that structured fixed bed padded with CMSM/PSSF composite offered higher adsorption rate and mass transfer efficiency.

High efficiency of toluene adsorption over a novel ZIF-67 membrane coating on paper-like stainless steel fibers

A novel microporous ZIF-67 membrane coating on paper-like stainless steel fibers (ZIF-67 membrane/PSSF) was successfully synthesized by a wet layup papermaking-sintering method followed by the seed-induced growth method. The effects of key factors such as crystallization temperature, synthesis time and Hmim/Co2+ (2-methylimidazole/cobalt chloride) molar ratio on the morphology structure of the samples were studied by the modern characterization techniques including SEM, EDX, TEM, XRD, BET, FTIR and TGA, respectively. The experimental result indicated that the as-synthesized ZIF-67 membrane/PSSF was extremely compact with the average membrane thickness of 4.8 μm. And the sample exhibited high BET surface area (440.9 m2/g), uniform pore size (1.881 nm) and large pore volume (0.2096 cm3/g). The adsorption breakthrough experiment of toluene was performed on different bed reactors filled with ZIF-67 membrane/PSSF and granular ZSM-5 zeolites, respectively. The experiment data was well fitted by Yoon–Nelson model, where the values of rate constant in the fixed bed with ZIF-67 membrane/PSSF increased by 32.2% compared with that of commercial ZSM-5 zeolites at the flow rate of 100 mL/min. And the bed pressure drop and length of unused bed (LUB) were dramatically reduced by 39.6% and 16.8% in 3 cm ZIF-67 membrane/PSSF fixed bed. In conclusion, mass transfer efficiency was significantly enhanced based the structured ZIF-67 membrane/PSSF fixed bed, and this new material is a promising adsorptive material for VOCs removal.

Catalytic combustion of methyl ethyl ketone over paper-like microfibrous entrapped MnOx/AC catalyst

A novel MnOx-deposited paper-like stainless steel fibers entrapped activated carbon catalyst (Mn-GAC/PSSF) was synthesized by papermaking technology and incipient wetness impregnation (IM) method for methyl ethyl ketone (MEK) combustion, and Mn-deposited granular activated carbon catalyst (Mn-GAC) was prepared simultaneously as a contrast. Characterization of all the samples were carried out by using X-ray diffraction patterns (XRD), N2 adsorption-desorption, scanning electron microscopy (SEM), H2-Temperature programmed reduction (TPR) and X-ray photoelectron spectra (XPS). SEM showed that the Mn oxides on the carbons were relatively well distributed as that on the stainless steel fibers. XPS indicated that the Mn coexisted as Mn3+ and Mn4+. The catalytic activity test for MEK combustion was carried out at atmospheric pressure in a continuous fixed bed stainless steel tube reactor, the results revealed that the Mn-GAC/PSSF catalysts were much more active than Mn-GAC catalyst due to the properties of excellent mass transfer and contacting efficiency offered by PSSF structure, and exhibited high selectivity for complete oxidation of intermediates. Catalyst with higher Mn loading presented higher catalyst activity, the conversion of MEK reached to 90% at 521 K over the 30%-Mn-GAC/PSSF catalysts, while it was 566 K and 530 K over the 10%-Mn-GAC/PSSF catalyst and 20%-Mn-GAC catalyst, respectively.

Preparation and characterization of a novel ZIF-8 membrane over high voidage paper-like stainless steel fibers

A new method was employed to synthesize a novel high voidage ZIF-8 membrane over paper-like stainless steel fibers (PSSF). Firstly, paper-like stainless steel fibers (PSSF) were prepared by wet lay-up papermaking and sintering process, then the ZIF-8 membrane was coated on the PSSF support by secondary growth process. The effects of the seed layer growth time, the Hmim (2-methylimidazole)/Zn (Zinc nitrate hexahydrate) molar ratios, the solvothermal synthesis temperature and time on properties of ZIF-8 membrane/PSSF composites were investigated by modern characterization methods. The experimental results indicated that the void volume of ZIF-8 membrane/PSSF composites reached 89%. The optimal specific surface area of composites was 398 m2/g and the total pore volume was 0.174 cm3/g. Specifically, the size of seeds were approximately 250 nm when Hmim/Zn molar ratios and seed layer deposition time were 80 and 12 h, respectively. Under the condition of optimal seed layer, ZIF-8 membrane/PSSF composites showed outstanding continuity, compactness, free-defect and crystal shape when solvothermal synthesis time and solvothermal synthesis temperature were 24 h and 100 °C, respectively.

High efficiency of isopropanol combustion over cobalt oxides modified ZSM-5 zeolite membrane catalysts on paper-like stainless steel fibers

Catalytic performances of isopropanol combustion and bed pressure drop in structured fixed bed reactor composed of cobalt oxides modified ZSM-5 zeolite membrane catalysts on paper-like stainless steel fibers (Co/ZSM-5/PSSF) and traditional granular ZSM-5 zeolites catalysts were investigated in this paper. Both of the catalyst samples were fabricated by wetness impregnation method and were characterized via X-ray diffraction (XRD), scanning electron microscopy (SEM) coupled with energy dispersive X-ray spectrometer (EDS) mapping and the N2 adsorption/desorption isotherm analyses. The result of EDS mapping revealed that cobalt oxides dispersed well on ZSM-5/PSSF. The Co/ZSM-5/PSSF catalyst display superior catalytic activity to granular Co/ZSM-5 catalyst, 50% and 90% isopropanol conversion temperatures over Co/ZSM-5/PSSF reduced 107°C and 51°C, respectively, compared with those over granular Co/ZSM-5 catalysts. The apparent activation energy for isopropanol combustion over Co/ZSM-5/PSSF (90kJ/mol) was much lower than that over granular Co/ZSM-5 (134kJ/mol). When the face velocity increased to 14.9cm/s, the bed pressure drop of reactor filled with only Co/ZSM-5/PSSF catalysts was 9.5% of that of reactor filled with only granular Co/ZSM-5 catalysts. The ZSM-5 zeolite membrane on paper-like stainless steel fibers support provide good dispersion for cobalt oxides and Co/ZSM-5/PSSF show superior catalytic efficiency of isopropanol combustion and produced lower bed pressure drop in reactor compared with granular ZSM-5 zeolites.

Catalytic combustion of isopropanol over Co-Mn mixed oxides modified ZSM-5 zeolite membrane catalysts coated on stainless steel fibers

Abstract A novel gradient porous Co-Mn mixed oxides modified ZSM-5 zeolite membrane/PSSF (paper-like stainless steel fibers) catalyst was prepared for catalytic combustion of isopropanol in a membrane reactor. First, the paper-like sintered stainless steel fibers (PSSF) support was fabricated by wet lay-up papermaking method and sintering process. Then, ZSM-5 zeolite membranes were synthesized on the surface of stainless steel fibers by using secondary growth process. Finally, the cobalt and manganese mixed oxides modified ZSM-5 zeolite membrane catalysts were prepared by wet impregnation method. These novel modified membrane catalysts were characterized by using SEM, XRD, N2 adsorption–desorption isotherms and XPS, respectively. The catalytic activity test was carried out over a membrane reactor filled with ZSM-5 zeolite membrane catalysts and granular catalysts, respectively. The experimental results showed that the junctures of stainless steel fibers were completely sintered together to form a three-dimensional network structure and ZSM-5 zeolite membrane was fabricated on the PSSF support with the thickness of 1.78 μm. The cobalt element existed as Co3+and Co2+, maganese element existed as Mn4+ and Mn3+. The results of catalytic activity tests showed that catalytic activity for isopropanol over ZSM-5 zeolite membrane catalyst was superior to that over granular ZMS-5 catalyst, the reaction temperature of 50% and 90% conversion of isopropanol over ZSM-5 zeolite membrane catalyst dramatically decreased. The Co-Mn(1:4)/ZSM-5/PSSF catalysts presented the most excellent catalytic activity for isopropanol combustion, compared with Co/ZSM-5/PSSF and Mn/ZSM-5/PSSF catalysts, respectively.

Catalytic combustion of volatile organic compounds over Co/ZSM-5 coated on stainless steel fibers

• A novel gradient porous Co/ZSM-5/PSSF catalyst was prepared. • The Co/ZSM-5/PSSF catalyst presents efficient activity for isopropanol oxidation. • Catalytic efficiency of Co/ZSM-5/PSSF is superior to granular Co/ZSM-5. Co/ZSM-5/PSSF (paper-like stainless steel fibers) catalyst was prepared for the catalytic combustion of volatile organic compounds (isopropanol). The cobalt oxides modified ZSM-5/PSSF catalyst was synthesized by wet impregnation method, and the ZSM-5/PSSF was prepared via secondary growth method on the surface of PSSF supports which was made by wet lay-up papermaking method and sintering process. Characterization of all the samples was carried out by means of X-ray diffraction (XRD), scanning electron microscope (SEM), energy disperse X-ray spectrometer (EDS) mapping, X-ray photoelectron spectrum (XPS), N 2 adsorption/desorption and H 2 -temperature programmed reduction (H 2 -TPR). The results of EDS demonstrated that cobalt oxides had a perfect dispersion on the surface of ZSM-5/PSSF. The performance of catalytic oxidation of single VOCs (isopropanol) was conducted over a zeolite membrane reactor based on Co/ZSM/PSSF catalysts, the experimental results showed that the 0.5 M Co/ZSM-5/PSSF-500 °C catalyst exhibited the best catalytic activity for isopropanol oxidation with 90% conversion of isopropanol at 222 °C with the feed concentration of 4.5 mg/L and GHSV of 7643 h −1 , which was much lower than that of granular Co/ZSM-5 catalyst (293 °C). The special pore structure of ZSM-5/PSSF can offer a relatively higher contacting efficiency, lower diffusion resistance and reasonable mass/heat transfer efficiency.