Chemical Vapor Deposition of Hollow Graphitic Spheres for Improved Electrochemical Durability

The wet-chemical synthesis of hollow graphitic spheres, a highly defined model catalyst support for electrocatalytic processes, is laborious and not scalable, which hampers potential applications. Here, we present insights into the chemical vapor deposition (CVD) of ferrocene as a simple, scalable method to synthesize hollow graphitic spheres (HGScvd). During the CVD process, iron and carbon are embedded in the pores of a mesoporous silica template. In a subsequent annealing step, iron facilitates the synthesis of highly ordered graphite structures. We found that the applied temperature treatment allows for controlling of the degree of graphitization and the textural properties of HGScvd. Further, we demonstrate that platinum loaded on HGScvd is significantly more stable during electrochemical degradation protocols than catalysts based on commercial high surface area carbons. The established CVD process allows the scalable synthesis of highly defined HGS and therefore removes one obstacle for a broader application

Oxidation of Bioethanol using Zeolite-Encapsulated Gold Nanoparticles

With the ongoing developments in biomass conversion, the oxidation of bioethanol to acetaldehyde may become a favorable and green alternative to the preparation from ethylene. Here, a simple and effective method to encapsulate gold nanoparticles in zeolite silicalite‐1 is reported and their high activity and selectivity for the catalytic gas‐phase oxidation of ethanol are demonstrated. The zeolites are modified by a recrystallization process, which creates intraparticle voids and mesopores that facilitate the formation of small and disperse nanoparticles upon simple impregnation. The individual zeolite crystals comprise a broad range of mesopores and contain up to several hundred gold nanoparticles with a diameter of 2–3 nm that are distributed inside the zeolites rather than on the outer surface. The encapsulated nanoparticles have good stability and result in 50 % conversion of ethanol with 98 % selectivity toward acetaldehyde at 200 °C, which (under the given reaction conditions) corresponds to 606 mol acetaldehyde/mol Au hour−1

Is biotechnology (more) acceptable when it enables a reduction in phytosanitary treatments? A European comparison of the acceptability of transgenesis and cisgenesis

Reduced pesticide use is one of the reasons given by Europeans for accepting new genetic engineering techniques. According to the advocates of these techniques, consumers are likely to embrace the application of cisgenesis to apple trees. In order to verify the acceptability of these techniques, we estimate a Bayesian multilevel structural equation model, which takes into account the multidimensional nature of acceptability and individual, national, and European effects, using data from the Eurobarometer 2010 73.1 on science. The results underline the persistence of clear differences between European countries and whilst showing considerable defiance, a relatively wider acceptability of vertical gene transfer as a means of reducing phytosanitary treatments, compared to horizontal transfer

Cisgenesis and intragenesis as new strategies for crop improvement

Cisgenesis and intragenesis are emerging plant breeding technologies which offer great promise for future acceptance of genetically engineered crops. The techniques employ traditional genetic engineering methods but are confined to transferring of genes and genetic elements between sexually compatible species that can breed naturally. One of the main requirements is the absence of selectable marker genes (such as antibiotic resistance genes) in the genome. Hence the sensitive issues with regard to transfer of foreign genes and antibiotic resistance are overcome. It is a targeted technique involving specific locus; therefore, linkage drag that prolongs the time for crop improvement in traditional breeding does not occur. It has great potential for crop improvement using superior alleles that exist in the untapped germplasm or wild species. Cisgenic and intragenic plants may not face the same stringent regulatory assessment for field release as transgenic plants which is a clear added advantage that would save time. In this chapter, the concepts of cis/intragenesis and the prerequisites for the development of cis/intragenesis plants are elaborated. Strategies for marker gene removal after selection of transformants are discussed based on the few recent reports from various plant species

Formation of pyridine N-oxides using mesoporous titanium silicalite-1

Mesoporous titanium silicalite-1 (TS-1) prepared by carbon-templating is significantly more active than conventional TS-1 for the oxidation of pyridine derivatives using aqueous hydrogen peroxide as oxidant. The catalytic activity is increased by the system of mesopores that helps to overcome the configurational diffusion limitations within the microporous catalyst. The use of a carbon-template for generation of secondary porosity is more effective than desilication. The desilicated catalyst is slightly more active than conventional TS-1, probably due to a decrease of the mean diffusion path length. In contrast, carbon-templated mesopores provides an efficient transport throughout the zeolite, thus preventing deactivation due to product confinement. All catalysts were characterised by X-ray powder diffraction, scanning electron microscopy, UV–Vis spectroscopy and nitrogen physisorption. The results indicate that desilication may cause a surface densification of less catalytically active extra-framework Ti species. Carbon-templating is thus a more gentle and effective method for generating secondary porosity. Utilization of carbon-templated mesoporous TS-1 for oxidation of pyridine derivatives represents a new and environmentally friendly method to synthesise N-oxides.We gratefully acknowledge the support of the Danish Council for Independent Research, Grant No. 10-093717 and Grant No. 12-127580. We would also like to thank for support from the Spanish Ministry of Science and Innovation (project CTQ2011-25517), and Unidad de Apoyo from Catalysis Institute (ICP-CSIC).Peer Reviewe

Methanation of Carbon Dioxide over Zeolite-Encapsulated Nickel Nanoparticles

Efficient methanation of CO2 relies on the development of more selective and stable heterogeneous catalysts. Herein, we present a simple and effective method to encapsulate Ni nanoparticles in zeolite silicalite‐1. In this method, the zeolite is modified by selective desilication, which creates intraparticle voids and mesopores that facilitate the formation of small and well‐dispersed nanoparticles upon impregnation and reduction. Transmission electron microscopy and X‐ray photoelectron spectroscopy analyses confirm that a significant part of the Ni nanoparticles are situated inside the zeolite rather than on the outer surface. The encapsulation results in increased metal dispersion and, consequently, high catalytic activity for CO2 methanation. With a gas hourly space velocity of 60 000 mL gcatalyst−1 h−1 and H2/CO2=4, the zeolite‐encapsulated Ni nanoparticles result in 60 % conversion at 450 °C, which corresponds to a site‐time yield of approximately 304 molurn:x-wiley:18673880:media:cctc201701946:cctc201701946-math-0001  molNi−1 h−1. The encapsulated Ni nanoparticles show no change in activity or selectivity after 50 h of operation, although postcatalysis characterization reveals some particle migration

Chemical Vapor Deposition of Hollow Graphitic Spheres for Improved Electrochemical Durability

The wet-chemical synthesis of hollow graphitic spheres, a highly defined model catalyst support for electrocatalytic processes, is laborious and not scalable, which hampers potential applications. Here, we present insights into the chemical vapor deposition (CVD) of ferrocene as a simple, scalable method to synthesize hollow graphitic spheres (HGScvd). During the CVD process, iron and carbon are embedded in the pores of a mesoporous silica template. In a subsequent annealing step, iron facilitates the synthesis of highly ordered graphite structures. We found that the applied temperature treatment allows for controlling of the degree of graphitization and the textural properties of HGScvd. Further, we demonstrate that platinum loaded on HGScvd is significantly more stable during electrochemical degradation protocols than catalysts based on commercial high surface area carbons. The established CVD process allows the scalable synthesis of highly defined HGS and therefore removes one obstacle for a broader application

Chemical Vapor Deposition of Hollow Graphitic Spheres for Improved Electrochemical Durability

The wet-chemical synthesis of hollow graphiticspheres, a highly defined model catalyst support for electrocatalyticprocesses, is laborious and not scalable, which hampers potentialapplications. Here, we present insights into the chemical vapordeposition (CVD) of ferrocene as a simple, scalable method tosynthesize hollow graphitic spheres (HGScvd). During the CVDprocess, iron and carbon are embedded in the pores of amesoporous silica template. In a subsequent annealing step, ironfacilitates the synthesis of highly ordered graphite structures. Wefound that the applied temperature treatment allows for controllingof the degree of graphitization and the textural properties ofHGScvd. Further, we demonstrate that platinum loaded on HGScvdis significantly more stable during electrochemical degradationprotocols than catalysts based on commercial high surface area carbons. The established CVD process allows the scalable synthesisof highly defined HGS and therefore removes one obstacle for a broader application