Papermaking Technique Research Articles

Enhancing Mechanical Properties of Ceramic Papers Loaded with Zeolites using Borate Compounds as Binders

NaY zeolite-containing ceramic papers were prepared by a papermaking technique with a dual polyelectrolyte retention system that implied the use of cationic and anionic polymers. To improve their mechanical properties, we found that some borate compounds could be successfully used as ceramic binders. Three types of sodium and/or calcium borates were tested as binders: colemanite, nobleite, and anhydrous ulexite. The improvement in the mechanical properties depends both on the borate used and on the calcination temperature. By XRD it was determined that the faujasite structure collapsed after calcination at 700°C, which limited the final calcination temperature of zeolitic ceramic papers. Different amounts of NaY zeolite were added to ceramic papers and, as observed by SEM, faujasite particles were well distributed throughout the ceramic paper structure. Ceramic papers containing 1.2 wt.% zeolite after calcination at 650°C resulted in structured catalysts that were easy-to-handle, and which can be adapted to different conformations.

In Situ Synthesis of Bimetallic Hybrid Nanocatalysts on a Paper-Structured Matrix for Catalytic Applications

Bimetallic nanoparticles have attracted significant attention as their electrochemical and catalytic properties being superior to those of the individual component nanoparticles. In this study, gold-silver hybrid nanoparticles (AuAgNPs) with an Aucore-Agshell nanostructure were successfully synthesized on zinc oxide (ZnO) whiskers. The as-prepared nanocatalyst, denoted AuAgNPs@ZnO whisker, exhibits an excellent catalytic efficiency in the aqueous reduction of 4-nitrophenol to 4-aminophenol; the turnover frequency was up to 40 times higher than that of each component nanoparticle. Their unique features were attributed to the electronic ligand effect at the bimetallic interface. In addition, the AuAgNPs were synthesized on a ZnO whisker-containing paper with a fiber-network microstructure, which was prepared via a papermaking technique. The paper-structured AuAgNPs composite possessed both a paper-like practical utility and a good catalytic performance. Furthermore, the on-paper synthesis process for these bimetallic nanocatalysts is facile. These easy-to-handle nanocatalyst hybrid composites are expected to find a wide range of applications in various chemical and catalytic processes.

In situ synthesis of gold nanoparticles on zinc oxides preloaded into a cellulosic paper matrix for catalytic applications

This article describes a facile method for the preparation of cellulosic catalyst paper: the in situ synthesis of gold nanoparticles (AuNPs) on zinc oxide (ZnO) whiskers, the preferential support for AuNPs, preloaded into a paper matrix. The ZnO paper composites were fabricated using a high-speed and low-cost paper-making technique, and immersed in an aqueous solution of HAuCl4. After drying, fine 5 nm AuNPs were successfully formed on the ZnO whiskers inside the paper matrix. As-prepared AuNPs@ZnO whisker-containing paper (AuNPs@ZnO paper) is similar to ordinary paper products, being flexible, lightweight, and easy to handle. The AuNPs@ZnO paper exhibited a high catalytic efficiency towards the reduction of 4-nitrophenol to 4-aminophenol in aqueous media. Furthermore, the addition of a polyamideamine epichlorohydrin resin provided a wet strength to the AuNPs@ZnO paper, which enables several catalyst recycles with no significant losses in catalytic activity.

Ceramic papers containing Y zeolite for toluene removal

A papermaking technique with a dual polyelectrolyte retention system was used for the preparation of NaY zeolite-containing papers, which implied the use of cationic and anionic polymers. Two kinds of fibers were employed, either cellulosic or ceramic ones, and accordingly papers with different characteristics were obtained: those that only contained cellulosic fibers for low temperature applications, cellulosic papers, and those prepared using both cellulosic and ceramic fibers – ceramic papers – for high temperature applications. Although a decrease in their mechanical properties due to calcination was observed, zeolitic ceramic papers resulted easy to handle for practical applications. Zeolite was quantified through BET surface area measurements. SEM images indicated a good dispersion of zeolite particles within the cellulosic paper whereas in the ceramic paper they appeared anchored on ceramic fibers. The zeolitic papers prepared resulted efficient as toluene sorbents, the adsorption capacities of zeolitic ceramic papers being higher than those of zeolitic cellulosic papers. In the case of zeolitic cellulosic papers, the amounts of released toluene were lower than those of adsorbed toluene, implying that the treatment up to 160 °C did not completely eliminate the hydrocarbon. Also, TPD profiles showed that toluene is chemically retained up to high temperatures (ca. 420 °C) in zeolitic ceramic papers. Toluene adsorption values demonstrate that zeolite dispersed into the cellulose/ceramic matrix is as effective as powder massive zeolite in retaining the hydrocarbon, which highlights the potential application of these zeolitic structures as sorbent materials both for low and high temperatures.

Cellulose wet wiper sheets prepared with cationic polymer and carboxymethyl cellulose using a papermaking technique

Carboxymethyl cellulose (CMC)-rich cellulose sheets were prepared with a cationic retention aid, poly[N,N,N-trimethyl-N-(2-methacryloxyethyl)ammonium chloride] (PTMMAC), using a papermaking technique. When 5% PTMMAC and 5% CMC were added to cellulose slurries, approximately 94% of the polymers were retained in the sheets by formation of polyion complexes between the two polymers. When the PTMMAC/CMC/cellulose sheets were soaked in solutions consisting of ethanol, water and calcium chloride (EtOH/H2O/CaCl2) with a weight ratio of 75:24:1, almost all PTMMAC and CMC molecules remained in the sheets, forming the structures of PTMMAC-N+Cl− and CMC-COO−Ca2+Cl− without dissolution of these molecules in the soaking solution. Thus, PTMMAC, CMC and calcium contents in the sheets were able to be determined on the basis of these PTMMAC and CMC structures from analytical data such as nitrogen, calcium and chlorine contents. The trade-off properties between sufficient wet strength in use and water-disintegrability after use can be added to the PTMMAC/CMC/cellulose sheets by selecting weight ratios of the EtOH/H2O/CaCl2 solution used as the impregnation liquid.

One-step synthesis of gold nanocatalysts on a microstructured paper matrix for the reduction of 4-nitrophenol

The one-step synthesis of gold nanoparticles (AuNPs) was achieved, in situ, on a microstructured paper composite that consisted of ceramic fibers which acted as the main frame with zinc oxide (ZnO) whiskers being used as the selective support for the AuNPs. Initially, ZnO whiskers were incorporated into a ceramic paper matrix using a high-speed and low-cost papermaking technique, and the AuNPs were then synthesized onto the embedded ZnO whiskers via a simple soaking treatment using an aqueous solution of tetrachloroauric acid (HAuCl 4). The as-prepared hybrid material has the appearance of paperboard and is denoted as AuNPs@ZnO paper. It was lightweight, flexible, sufficiently strong and easy-to-handle in practical use, and possessed a paper-like porous microstructure. In the liquid-phase reduction process of 4-nitrophenol, the AuNPs@ZnO paper demonstrated excellent catalytic performance compared with conventional Au/ZnO catalyst powders. This suggests that the unique paper structure, which has an open pore system throughout the structure, promotes the efficient transport of the reactants to the surfaces of the highly effective AuNPs. Thus, this AuNPs@ZnO paper is expected to be a promising catalytic material having a high degree of practical utility and catalytic efficiency.

NO X reduction over paper-structured fiber composites impregnated with Pt/Al2O3 catalyst for exhaust gas purification

Pt/Al2O3 catalyst powder was successfully incorporated in a microstructured paper-like matrix composed of a ceramic fiber network, by use of a simple papermaking technique. As-prepared composite, denoted paper-structured catalyst, was applied to the reduction of nitrogen oxide (NO X ) in the presence of propene, for exhaust gas purification. The paper-structured catalyst demonstrated higher NO X reduction efficiency and more rapid thermal responsiveness than a conventional Pt-loaded honeycomb catalyst, indicating that the paper-like structure with interconnected pore spaces contributes to effective transport of heat and reactants to the catalyst surfaces. Furthermore, the paper-structured catalyst with the appearance of flexible paperboard has a high degree of utility. The efficiency of utilization of Pt catalyst was improved by using hierarchically assembled paper-structured catalysts with preferential location of Pt catalyst in the upper part. The paper-structured catalyst composite with paper-like utility and porous microstructure is thought to be a promising catalytic material for efficient NO X gas purification.

Reuse of polymer materials and carbon fibres in novel engineering composite materials

The present work was devoted to the development of a technique for manufacture of a novel engineering material from carbon fibres and thermoplastic matrix recyclates. Fibre preforms were manufactured employing a papermaking technique for dispersing the carbon fibres. The polypropylene (PP) matrix recyclate was reprocessed into a film. The carbon fibre preforms and PP films were stacked and composite materials were subsequently manufactured by press forming. The mechanical behaviour of carbon fibre preforms was characterised by a compaction test and compared to the results obtained by consolidation test of the carbon fibres reinforced PP composites. The consolidation experiments were found to follow the trend from compaction tests allowing prediction of the amount of polymer material needed, fibre volume fraction as well as composites thickness. The resulting dispersion of fibres and void content were evaluated by microscopy.

Preparation of ruthenium-containing sheet composites using a papermaking technique for selective oxidation of alcohol

Ruthenium (Ru) catalyst was introduced onto a glass fiber surface by ion-exchange, the treated fibers were made into Ru-containing sheet composites (referred to in this paper as Ru sheets) using a papermaking technique. Ru was easily introduced by mixing RuCl 3 aqueous solution into a glass fiber suspension and became strongly attached and immobilized on the fiber surface. Ru sheet is easy to handle and is strong enough to use for chemical reactions in organic solvents. X-ray photoelectron spectroscopy and atomic adsorption analyses revealed that the Ru attachment was not simple adsorption but due to an ion-exchange mechanism. Pieces of Ru sheet were used to catalyze selective oxidation of benzyl alcohol to produce acetaldehyde and demonstrated a higher performance than commercial Ru-containing catalyst powders. The porous sheet structure seemed to improve the effective transport of benzyl alcohol to inside of the sheet, resulting in enhanced catalytic performance. Thus Ru sheet demonstrates both practical convenience and a high level of catalytic activity when compared with currently available alternative materials.

Influence of a fiber-network microstructure of paper-structured catalyst on methanol reforming behavior

A novel microstructured catalyst that consists of Cu/ZnO catalyst powders and ceramic fibers was successfully prepared using pulp fibers as a tentative matrix by a papermaking technique. As-prepared material, called a paper-structured catalyst, possessed porous microstructure with layered ceramic fiber networks (average pore size ca. 20 μm, porosity ca. 50%). In the process of methanol autothermal reforming (ATR) to produce hydrogen, paper-structured catalysts demonstrated both high methanol conversion and low concentration of undesirable carbon monoxide as compared with catalyst powders and pellets. The catalytic performance of paper-structured catalysts depended on the use of pulp fibers, which were added in the paper-forming process and finally removed by thermal treatment before ATR performance tests. Confocal laser scanning microscopy and mercury intrusion analysis suggested that the tentative pulp fiber matrix played a significant role in regulating the fiber-network microstructure inside paper composites. Various metallic filters with different average pore sizes, used as supports for Cu/ZnO catalysts, were subjected to ATR performance tests for elucidating the pore effects. The tests indicated that the pore sizes of catalyst support had critical effects on the catalytic efficiency: the maximum hydrogen production was achieved by metallic filters with an average pore size of 20 μm. These results suggested that the paper-specific microstructures contributed to form a suitable catalytic reaction environment, possibly by promoting efficient diffusion of heat and reactants. The paper-structured catalyst with a regular pore microstructure is expected to be a promising catalytic material to provide both practical utility and high efficiency in the catalytic gas-reforming process.

Paper-structured catalyst for catalytic [formula omitted] removal from combustion exhaust gas

Platinum/aluminum oxide (Pt/Al 2O 3) catalyst powders were successfully fabricated to give paper-like composites using ceramic fibers by a papermaking technique. As-prepared composites, called paper-structured catalysts, possessed a fiber-network microstructure on which the Pt/Al 2O 3 powders were scattered. The paper-structured catalysts were subjected to a catalytic reduction process of nitrogen oxides ( NO x ), and demonstrated a higher performance than the original Pt/Al 2O 3 powders and a commercial honeycomb catalyst. A simple mixture of catalyst powders and inorganic fibers was not effective, suggesting that the characteristic porous microstructure (average pore size: ca. 20 μ m , porosity: ca. 70%) in the paper-structured catalyst possibly contributed to the efficient NO x reduction. Besides, the paper-structured catalyst exhibited a quick response in the catalytic NO x reduction at a rapidly increasing reaction temperature as compared to the honeycomb catalyst. The paper composite is flexible, lightweight and easy to handle; thus the paper-structured catalyst is expected to be a promising catalytic material for exhaust gas purification.

Paper-structured fiber composites impregnated with platinum nanoparticles synthesized on a carbon fiber matrix for catalytic reduction of nitrogen oxides

Platinum nanoparticles (PtNPs) were synthesized on surface-activated carbon fibers with high thermal conductivity, and paper-structured composites were fabricated by a papermaking technique, using the PtNPs-supported carbon fibers and ceramic fibers as matrix materials. As-prepared materials, denoted paper-structured PtNPs catalyst, possessed a unique porous microstructure derived from entangled inorganic fiber networks on which PtNPs were well dispersed. In catalytic reduction of nitrogen oxides (NOX) in the presence of methane (CH4), both of which are model exhaust gas components of combustion engines, paper-structured PtNPs catalyst demonstrated excellent NOX and CH4 removal efficiency and rapid thermal responsiveness by comparison with the PtNPs-supported carbon fibers, commercial Pt catalyst powders and a monolithic Pt-loaded honeycomb. These features of the new catalyst material are thought to arise from synergistic effects of the highly active PtNPs in association with the unique paper-like microstructure, in promoting effective transfer of heat and reactants to the active sites of the Pt nanocatalysts. The paper-structured PtNPs catalyst with paper-like practical utility is expected to be a promising catalytic material for efficient NOX gas purification.

Selective oxidation of benzyl alcohol using RuHAp-containing sheet composites

Ru-containing hydroxyapatite (RuHAp) powder was successfully impregnated into sheet composites using a papermaking technique, and its catalytic efficiency was investigated. The RuHAp powder was homogeneously scattered over the fiber-mix networks that had been tailored within the catalyst sheet. RuHAp-containing sheets demonstrated superior performance to RuHAp beads for the selective oxidation of benzyl alcohol to benzaldehyde in a batch reaction process and the efficiency was equivalent to that of RuHAp powder. Catalytic performance was also evaluated in a continuous fixed-bed column reactor and RuHAp sheets showed higher oxidation efficiency than both RuHAp powder and beads. The porous structure of composites seemed to improve the effective transport of benzyl alcohol to RuHAp surfaces which were immobilized within the sheets, resulting in enhanced catalytic performance.

On-paper synthesis of Au nanocatalysts from Au(III) complex ions for low-temperature CO oxidation

Au nanoparticles (AuNPs) were successfully synthesized in situ on a microstructured paper matrix composed of ceramic fibers as the main framework and ZnO whiskers as a preferential support for AuNPs. The paper-like ceramic fiber/ZnO whisker composites were prepared using a papermaking technique, then soaked in an aqueous solution of the Au(III) complex HAuCl4. AuNPs with size <10 nm were spontaneously formed on the ZnO whiskers in the absence of reducing agents, possibly due to electron transfer from Zn(II) in ZnO whiskers to Au(III) species through Zn–O–Au bonds. As-prepared AuNPs@ZnO whisker-containing paper (AuNPs@ZnO paper) is much like ordinary paper products in being flexible, lightweight and easy to handle. AuNPs@ZnO paper demonstrated excellent catalytic performance in low-temperature CO oxidation. Complete conversion of CO to CO2 was achieved at 20 °C, 140 K lower than the reaction temperature for conventional Au/ZnO catalyst powders. This facile technique has potentially broad wide applications in ‘on-paper’ synthesis of a diverse array of metal NPs. The metal NPs@ZnO paper composites with paper-like flexibility are able to fit various reactor configurations and are thus expected to be promising catalytic materials for improving the practical utility and catalytic performance of these systems, for a wide range of industrial chemical processes.

In situ synthesis of silver nanoparticles on zinc oxide whiskers incorporated in a paper matrix for antibacterial applications

Silver nanoparticles (AgNPs) were successfully synthesized in situ on a paper matrix composed of ceramic fibers as the main framework and zinc oxide (ZnO) whiskers as a selective support for AgNPs. Paper-like ceramic fiber/ZnO whisker composites were prepared in advance using a high-speed, low-cost papermaking technique, then immersed in an aqueous solution of silver nitrate for 6 h. AgNPs with particle size 5–20 nm were spontaneously formed on the ZnO whiskers through selective ion-exchange between Ag and Zn species, and simultaneous ZnO-mediated photo-reduction under natural light irradiation. As-prepared material (AgNPs@ZnO paper) was subjected to antibacterial assay by the disk diffusion method using Escherichia coli. The AgNPs@ZnO paper exhibited excellent antibacterial activity and durability for repeated use, as compared with paper composites containing either ionic Ag components or commercial crystalline Ag microparticles. The facile and direct synthesis of AgNPs on a paper-like matrix is a unique approach for the immobilization of highly active metal NPs onto easy-to-handle support materials, and the AgNPs@ZnO paper is expected to be a promising bioactive material having both antibacterial function and paper-like utility.

Antibacterial Activity of Compounded Papers using Wasted Green Tealeaves Produced by Paper-making Method

Various studies were conducted to improve antibacterial properties of compounded papers using wasted green tealeaves prepared by a paper-making technique. The research included the elucidation of a cause of low antibacterial activity. Different binders and different degrees of grinding wasted tealeaves were tested with no effect on antibacterial properties of compounded papers using wasted green tealeaves. However, when a suspension of pulp and wasted tealeaves was air-dried and used to prepare a compounded paper, the compounded paper was found to have excellent antibacterial properties. The result indicated a cause for the low antibacterial activity of compounded papers using wasted green tealeaves prepared by the paper-making technique. That is, catechins abundant in wasted green tealeaves dissolved in water when ground and ran off with waste water during the paper-making process without settling in compounded papers. To confirm that, liquid from a mass-colloider used for wet-grinding wasted tealeaves was sampled and filtered. The filtrate was dropped onto a 100 wt% pulp paper. No viable bacterial cell was found in the pulp paper to which more than 1.0 ml/g of the filtrate was applied ; the result showed that the liquid possessed good antibacterial properties. In other words, the liquid was confirmed to possess a high antibacterial activity. In paper making by the paper-making technique, aluminum sulfate was added to a suspension of pulp and ground, wasted tealeaves in order to readily settle catechins contained in liquid resulting from grinding wasted tealeaves in compounded papers using wasted tealeaves. The result revealed that a 2.70 wt% addition of aluminum sulfate to compounded papers using wasted green tealeaves improved antibacterial properties of the papers.

Paper-structured catalyst with porous fiber-network microstructure for autothermal hydrogen production

Abstract Copper–zinc oxide catalyst powders were supported on a microstructured matrix composed of ceramic fiber-network by a papermaking technique. As-prepared catalyst materials, called paper-structured catalyst, were applied to the autothermal reforming (ATR) of methanol to produce hydrogen for fuel cell applications. The paper-structured catalyst demonstrated higher methanol conversion and lower undesirable carbon monoxide concentration, as compared with commercial catalysts. Besides, excellent catalyst durability was exhibited by the suppression of Cu sintering during the ATR reaction. The paper-structured catalyst showed remarkable superiority in methanol conversion even in the case of using sintered catalysts. Such features were possibly induced by the unique fiber-network microstructure (average pore size: ca. 20 μm and porosity: ca. 50%) of the paper composites, which may allow the effective transfer of heat and reactants to the catalyst surfaces. The porous paper-structured catalyst is expected as a promising catalytic material for improving the practical performances in the catalytic gas-reforming process.

Preparation of porous sheet composite impregnated with TiO2 photocatalyst by a papermaking technique

Titanium dioxide (TiO2) powder-containing sheet composites, called TiO2 sheet, were prepared by a papermaking technique, and their photocatalytic efficiency was investigated. The TiO2 powders were homogeneously scattered over the fiber-mix networks tailored within the catalyst sheet. Under UV irradiation, the TiO2 paper could decompose p-hydroxyacetophenone (p-HAP), although the degradation efficiency by the TiO2 sheet was lower than that by the TiO2 powder. Scanning electron microscopy revealed that coverage of the TiO2 particles inside the sheet by alumina binder which was used to improve the sheet strength caused the deterioration of the photocatalytic performance. Internal addition of alumina binder made the TiO2 sheet porous and such a TiO2 sheet exhibited high photocatalytic performance equivalent to that of TiO2 powder. The porous structure of TiO2 sheet might contribute to effective transport of p-HAP to the surface of TiO2 particles inside the sheet, resulting in high degradation performance. In addition, TiO2 sheet prepared using TiO2 sol showed higher photocatalytic efficiency than TiO2 powder and it was indicated that the porous sheet structure might provide suitable conditions for TiO2 catalysis for photodecomposition.

Development of Functional Heating Sheet by Using a Paper-making Technique

Development of Functional Heating Sheet by Using a Paper-making Technique

Effect of void structure of photocatalyst paper on VOC decomposition

TiO 2 powder-containing paper composites, called TiO 2 paper, were prepared by a papermaking technique, and their photocatalytic efficiency was investigated. The TiO 2 paper has a porous structure originating from the layered pulp fiber network, with TiO 2 powders scattered on the fiber matrix. Under UV irradiation, the TiO 2 paper decomposed gaseous acetaldehyde more effectively than powdery TiO 2 and a pulp/TiO 2 mixture not in paper form. Scanning electron microscopy and mercury intrusion analysis revealed that the TiO 2 paper had characteristic unique voids ca. 10 μm in diameter, which might have contributed to the improved photocatalytic performance. TiO 2 paper composites having different void structures were prepared by using beaten pulp fibers with different degrees of freeness and/or ceramic fibers. The photodecomposition efficiency was affected by the void structure of the photocatalyst paper, and the initial degradation rate of acetaldehyde increased with an increase in the total pore volume of TiO 2 paper. The paper voids presumably provided suitable conditions for TiO 2 catalysis, resulting in higher photocatalytic performance by TiO 2 paper than by TiO 2 powder and a pulp/TiO 2 mixture not in paper form.