Steam reforming of ethanol over bimetallic RhPt/La2O3: Long-term stability under favorable reaction conditions

Recently, the steam reforming of biofuels has been presented as a potential hydrogen source for fuel cells. Because this scenario represents an interesting opportunity for Colombia (South America), which produces large amounts of bioethanol, the steam reforming of ethanol was studied over a bimetallic RhPt/La2O3 catalyst under bulk mass transfer conditions. The effect of temperature and the initial concentrations of ethanol and water were evaluated at space velocities above 55,000 h−1 to determine the conditions that maximize the H2/CO ratio and reduce CH4 production while maintaining 100% conversion of ethanol. These requirements were accomplished when 21 mol% H2O and 3 mol% C2H5OH (steam/ethanol molar ratio = 7) were reacted at 600 °C. The catalyst stability was assessed under these reaction conditions during 120 h on stream, obtaining ethanol conversions above 99% during the entire test. The effect of both H2 and air flows as catalyst regeneration treatments were evaluated after 44 and 67 h on stream, respectively. The results showed that H2 treatment accelerated catalyst deactivation, and air regeneration increased both the catalyst stability and the H2 selectivity while decreasing CH4 generation. Fresh and spent catalyst samples were characterized by TEM/EDX, XPS, TPR, and TGA. Although the Rh and Pt in the fresh catalyst were completely reduced, the spent samples showed a partial oxidation of Rh and small amounts of carbonaceous residue. A possible Rh–Pt–Rh2O3 structure was proposed as the active site on the catalyst, which was regenerated by air treatment.

Learning Probabilistic Features for Robotic Navigation Using Laser Sensors

SLAM is a popular task used by robots and autonomous vehicles to build a map of an unknown environment and, at the same time, to determine their location within the map. This paper describes a SLAM-based, probabilistic robotic system able to learn the essential features of different parts of its environment. Some previous SLAM implementations had computational complexities ranging from O(Nlog(N)) to O(N2), where N is the number of map features. Unlike these methods, our approach reduces the computational complexity to O(N) by using a model to fuse the information from the sensors after applying the Bayesian paradigm. Once the training process is completed, the robot identifies and locates those areas that potentially match the sections that have been previously learned. After the training, the robot navigates and extracts a three-dimensional map of the environment using a single laser sensor. Thus, it perceives different sections of its world. In addition, in order to make our system able to be used in a low-cost robot, low-complexity algorithms that can be easily implemented on embedded processors or microcontrollers are used.

Steamboats and pleasure travels: success and failure of the first Spanish initiatives in the mid-nineteenth century

Steam technology revolutionised maritime transport during the nineteenth century. Together with the establishment of the first regular lines, steamers soon led to the commencement of pleasure navigation. The aim of this article is to analyse the impact and scope of this process in Spain, by means of a study of the first experiences in the mid-nineteenth century. In addition to a brief introduction and final conclusions, the paper is structured around four sections. The first contains an appraisal of the situation of passenger transport. Some information is then provided regarding the first cruise in 1854. Next, the essay highlights some of the features of short excursions that were very well received by the public, especially in the island of Majorca. Finally, attention is given to a very special type of travel, the main attraction of which lay in the opportunity to witness an event of a military nature.

Hydrogen Production by Steam Reforming of Ethanol on Rh-Pt Catalysts: Influence of CeO2, ZrO2, and La2O3 as Supports

CeO2-, ZrO2-, and La2O3-supported Rh-Pt catalysts were tested to assess their ability to catalyze the steam reforming of ethanol (SRE) for H2 production. SRE activity tests were performed using EtOH:H2O:N2 (molar ratio 1:3:51) at a gaseous space velocity of 70,600 h−1 between 400 and 700 °C at atmospheric pressure. The SRE stability of the catalysts was tested at 700 °C for 27 h time on stream under the same conditions. RhPt/CeO2, which showed the best performance in the stability test, also produced the highest H2 yield above 600 °C, followed by RhPt/La2O3 and RhPt/ZrO2. The fresh and aged catalysts were characterized by TEM, XPS, and TGA. The higher H2 selectivity of RhPt/CeO2 was ascribed to the formation of small (~5 nm) and stable particles probably consistent of Rh-Pt alloys with a Pt surface enrichment. Both metals were oxidized and acted as an almost constant active phase during the stability test owing to strong metal-support interactions, as well as the superior oxygen mobility of the support. The TGA results confirmed the absence of carbonaceous residues in all the aged catalysts.