Molecular sieves for improved hydrocarbon traps

Molecular sieves and the use of such materials as hydrocarbon traps, particularly for reducing the emissions associated with the combustion of hydrocarbon fuels are described. Specifically, the use of molecular sieves such as zeolites as adsorbents for hydrocarbon gases, especially exhaust gases such as are formed during the combustion of hydrocarbons, and more particularly to the adsorption of hydrocarbon gases formed during the cold start operation of an internal combustion engine is described. In one embodiment, a method of treating exhaust gas that comprises a hydrocarbon combustion product is provided, the method comprising contacting the exhaust gas with a CON topology molecular sieve for a time period effective to facilitate adsorption of the hydrocarbon combustion product by the molecular sieve; passing a purge gas through the molecular sieve to remove adsorbed hydrocarbon combustion product; and contacting the purge gas containing the removed hydrocarbon combustion product with a hydrocarbon conversion catalyst

Synthesis and textural properties of unsupported and supported rutile (TiO2) membranes

Two approaches were postulated for improving the stability of porous texture of titania membranes: (1) retarding the phase transformation and grain growth; (2) avoiding the phase transformation. Based on the second approach, rutile membranes were made directly from a rutile sol, prepared by the precipitation of titania on SnO2 nuclei. The rutile membranes were stable up to 800 °C, with a porosity of ca. 40%, whereas normal titania membranes (starting with anatase) show very little porosity above 600 °C. Alumina substitution retards grain growth and pore growth at 850 °C for unsupported as well as supported membranes. \u

High-temperature catalyst supports and ceramic membranes: Metastability and particle packing

Parameters and/or processes responsible for the stability of catalyst supports and ceramic membranes are discussed. Two major parameters/processes were identified which are responsible for the stability of sol-gel derived nanostructured oxides at elevated temperatures. They are metastable-to-stable phase transformation and structure and packing of primary particles within the aggregate. Based on these observations, strategies to develop thermostable nanostructured oxides for high-temperature membrane and catalyst applications are discussed by taking titania and titania-alumina nanocomposites as examples

Textural evolution and phase transformation in titania membranes: Part 2. - Supported membranes

Nanostructural evolution and phase transformation in supported and unsupported titania membranes have been studied using Raman spectroscopy, X-ray diffraction (XRD) and field-emission scanning electron microscopy (FE-SEM). Densification of unsupported membranes started at ca. 450 °C and reached more than 97% density at 600 °C, whereas the supported membranes had a density of only ca. 70–75% even at 700 °C when calcined for 8 h. At 700 °C the average crystallite size of supported and unsupported membranes was ca. 20 and 70 nm, respectively. This behaviour is primarily attributed to the decrease in the driving force for sintering due to the stress developed during the constrained sintering of a film attached to a rigid support and to the inhibition of the reorganization process within the film, resulting in lower coordination numbers in supported membranes. Supported membranes showed a higher transformation temperature (slower rate of transformation) than did the unsupported. Supported and unsupported membranes, calcined for 8 h, transformed to ca. 90% rutile (calculated from Raman spectrum) after calcination at 850 and 650 °C, respectively. This difference in phase transformation behaviour is attributed primarily to the large stress which is developed in a constrained environment owing to the negative volume change during the anatase–rutile transformation

Evolution of pore structure in microporous silica membranes:sol-gel procedures and strategies

Silica membranes exhibiting excellent molecular sieving capability, which would find applications in fuel‐cell electric vehicles with on‐board hydrogen generation, for example, are the aim of the sol‐gel strategies outlined here. It is shown that optimization of the sol‐gel synthesis parameters is important in order to achieve membranes with minimum defects and hence high selectivity. The preparation of the supported membranes is described and the gas permeation behavior of membranes made from different sol compositions reported

Molecular sieves for improved hydrocarbon traps

Molecular sieves and the use of such materials as hydrocarbon traps, particularly for reducing the emissions associated with the combustion of hydrocarbon fuels are described. Specifically, the use of molecular sieves such as zeolites as adsorbents for hydrocarbon gases, especially exhaust gases such as are formed during the combustion of hydrocarbons, and more particularly to the adsorption of hydrocarbon gases formed during the cold start operation of an internal combustion engine is described. In one embodiment, a method of treating exhaust gas that comprises a hydrocarbon combustion product is provided, the method comprising contacting the exhaust gas with a CON topology molecular sieve for a time period effective to facilitate adsorption of the hydrocarbon combustion product by the molecular sieve; passing a purge gas through the molecular sieve to remove adsorbed hydrocarbon combustion product; and contacting the purge gas containing the removed hydrocarbon combustion product with a hydrocarbon conversion catalyst

TPA+-Mediated Conversion of Silicon Wafer into Preferentially-Oriented MFI Zeolite Film under Steaming

TPA^+-mediated conversion of silicon wafers into preferentially oriented siliceous MFI zeolite films is achieved by steam-assisted crystallization. Indeed, silicon wafers as the substrate are oxidized by TPAOH(aq) and therefore supplied as Si source for simultaneous crystallization of zeolite film

TPA+-Mediated Conversion of Silicon Wafer into Preferentially-Oriented MFI Zeolite Film under Steaming

TPA^+-mediated conversion of silicon wafers into preferentially oriented siliceous MFI zeolite films is achieved by steam-assisted crystallization. Indeed, silicon wafers as the substrate are oxidized by TPAOH(aq) and therefore supplied as Si source for simultaneous crystallization of zeolite film

Volcanic magma reservoir imaged as a low-density body beneath Aso volcano that terminated the 2016 Kumamoto earthquake rupture

Additional file 2: Figure S2. Calculated density contrast models beneath Aso volcano in horizontal slices at depths of 3.1, 4.9, and 8.2 km: (a), (b), (c), (d), (e), and (f) correspond to density contrasts of ±0.15, ±0.20 ±0.25, ±0.30, ±0.35, and ±0.40 g/cm3, respectively (Additional file 5: Table S1)