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A general method to prepare a catalytic coating on the surface of stainless steel microreactors has been developed. The catalytic support consists of a layer of randomly oriented, highly accessible carbon nanofibers (CNFs), directly grown on the surface of the channels by chemical vapor deposition (CVD) of ethanol. These CNFs are functionalized to acquire a positive charge before a solution containing metallic nanoparticles (Pt) is flown through the channels. The nanoparticles adhere to the surface of the CNFs thanks to electrostatic interactions. This process is carried out in-situ and the method can be easily adapted to larger scale production. These catalyst-coated microchannel reactors have been tested in the selective oxidation (SELOX) of CO in the presence of H2. The results were compared to those obtained in a conventional fixed bed reactor packed with Pt/CNTs. The microreactor clearly outperformed the fixed bed reactor at the same space velocity (WSHV = 2220 l/h gPt),), achieving total CO conversion at temperatures 50 oC lower.

Nd-doped titania materials prepared using a mild microwave-assisted protocol have been found to possess excelling activities in the photodegradation of water contaminants including phenol and Rhodamine B. These materials were characterized by a number of techniques including N 2 adsorption, X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS). The prepared materials showed high surface area, with the highest value for the catalyst containing a Nd/Ti ratio of 0.03 (341 m 2 /g). The dopant agent was found to be as Nd 3+ ions located on the surface and in the inter-planar space of titanium oxide crystals. Effects of the surface area together with the Nd content and the adsorption ability of the material seem to be involved in the optimum photocatalytic activity found for 0.5%Nd (Nd0.005/TiO 2 ) and 6%Nd (Nd0.06/TiO 2 ) containing materials.

The selective oxidation of CO in the presence of H2O and CO2 has been studied on Pt supported on different zeolitic materials (MOR, ZSM-5, FAU and ETS-10) using a range of operating conditions and a variety of characterization techniques. The behavior of the Pt–ETS-10 and Pt–FAU catalysts has been investigated in more depth and the results obtained have been compared and related to the different characteristics of the supports. The best results in the presence of H2O and CO2 were obtained with Pt–FAU catalysts, showing stable catalytic activity and complete conversion of CO (λ = 2) at 439 K.

Zeolite ZSM-5 layers (up to ca. 30% by weight) have been synthesized on cordierite substrates, following either a direct hydrothermal synthesis procedure or a secondary growth method, in this case after seeding of the support. The Si/Al ratio in the synthesis gel ranged from 14 to 100, but layers with a high Al content (i.e. a low Si/Al ratio) could not be prepared directly on the cordierite support. However, MFI layers with a low Si/Al ratio were readily grown after depositing an intermediate Si-rich layer. The results also show that the Si/Al ratio of the synthesis gel has a direct effect on the morphology, crystallinity and orientation of the MFI layer formed.

The favourable effect of adding CO 2 to the feed of reactors used for the oxidation of butane to maleic anhydride (MA) was reported previously [Appl. Catal. A 210 (2001) 271], although a clear explanation was not given. Also in the present work, a clear increase in the selectivity and yield to MA was observed upon addition of CO 2 , using two different membrane reactor configurations. The effect was more marked in the presence of high butane concentrations. From the results presented, it is concluded that CO 2 can oxidise the catalyst surface under the conditions used, rendering it more selective.

The deactivation of a Pd/SiO 2 catalyst by H 2 S during the hydrogenation of 1,3-butadiene and its subsequent reactivation have been studied. The poisoning effect of H 2 S on Pd catalysts during C 4 H 6 hydrogenation strongly decreased when the temperature of reaction was increased from 373 K to 508 K, due to the competition of butadiene for H 2 S chemisorption sites. The presence of H 2 S on the Pd sites causes an important decrease in the selectivity of the catalyst for a given conversion level. On the other hand, the irreversible adsorption of butadiene on Pd gives rise to an additional deactivation, and also to an increase in the observed selectivity. Reactivation of pre-poisoned catalysts can be performed at temperatures starting from around 400 K. The rate of sulfur desorption leading to catalyst reactivation strongly depends on the reaction atmosphere during the reactivation period, as well as on the temperature. During the reactivation stage, a high selectivity to butenes was observed, in spite of the presence of sulfur.

The activation-deactivation behaviour of a Cu/SiO2 catalyst during isopropyl alcohol (IPA) dehydrogenation to acetone has been studied. Simultaneous reduction and sintering processes are responsible for the activation-deactivation behaviour observed. The reducing H2 atmosphere impulses the transformation of CuO into Cu0 and at the same time the sintering of the Cu0 phase formed. The reoxidation treatment in air at 573–673 K is able to regenerate a finely dispersed CuO phase from the sintered Cu0 phase. As a result, the active phase is redispersed and the dehydrogenation activity is recovered. The results indicate the existence of two CuO phases on the catalyst, with different properties. The CuO phase with a low reduction temperature, a small particle size and a poor crystallinity, is the one responsible for the appearance of the finely dispersed Cu0, which is the active phase for this reaction.