Development and testing of a combined catalyst/sorbent core-in-shell material for the production of high concentration hydrogen

A combined catalyst and sorbent for the production of hydrogen from CH4 or CO was developed and tested. The combined catalyst and sorbent was a spherical multi-layered material having a CaO-based sorbent core and an outer shell composed mainly of alumina. The CaO sorbent core was employed to absorb CO2, one of the reaction products. The alumina shell protected the friable CaO core and also supported a Ni catalyst. The development of the material focused separately on the development of the core and shell. First, since the CO2 absorption capacity of CaO-based sorbents diminishes as they are repeatedly used and regenerated, the development of a more stable CaO-based sorbent was investigated. Both the addition of MgO, which acted as a sintering inhibitor, and severe initial calcination conditions for the CaO precursor limestone produced a more stable CaO sorbent. Second, an alumina-based material with good physical strength and high surface area was developed to serve as the shell of the core-in-shell material. The addition of either fine particle limestone or lanthanum oxide to the alumina shell formulation produced a material with enhanced physical strength, which was most likely due to the formation of a binding aluminate phase. Reaction testing of the core-in-shell pellets with a 3:1 molar ratio of H2O:CH4 in the feed produced a high concentration of H2 via simultaneous application of the steam-methane reforming reaction, the water-gas shift reaction and the reaction of CO2 with CaO. This testing was conducted with a tubular fixed bed reactor over a temperature range of 550-650yC and a pressure range of 1.0-10.0 atm. The rapid absorption of CO2 by CaO produced CH4 and CO conversions greater than would have been possible without a sorbent. Lifecycle testing determined that a high concentration of H2 could be produced over 10 cycles of H2 production and sorbent regeneration. However, the length of time that H2 was produced diminished with each cycle due to a loss of CO2 absorption capacity by the CaO sorbent. Physical characterization of the pellets after lifecycle testing also revealed that some pellets fractured during lifecycle testing and that the Ni catalyst sintered. Core-in-shell pellets with alternate shell formulations were also tested in the fixed bed reactor for the production of high concentrations of H2 from a mixture of CO and steam via the water-gas shift reaction. Three alumina shell formulations were tested: a formulation with mostly alumina in the shell, a formulation with 10 wt% Fe2O3 added to the alumina shell formulation and a formulation with Ni impregnated onto the shell. The rapid absorption of CO2 by the sorbent allowed for a high concentration of H2 to be produced and a high CO conversion to be achieved between 550-600yC at 1.0 atm with any of these formulations. However, once the CaO sorbent became loaded, only the formulation with Ni present converted CO to reaction equilibrium levels. On the other hand, by absorbing CO2 the formulation with mainly alumina in the shell appeared to be an attractive material for the production of H2 from syngas. Furthermore, this formulation would be resistant to sulfurous gases that might be present

Development of a combined catalyst and sorbent for the water gas shift reaction

A combined catalyst and sorbent was developed for reacting CO with steam to produce H2 in a single reaction stage at 600 °C by employing the water gas shift (WGS) reaction. The combined material was in the form of spherical pellets where each pellet consisted of a CaO core for absorbing byproduct CO2 surrounded by a porous shell of Al2O 3 which supported a Ni catalyst. The best results were achieved by incorporating 5 wt % limestone in the shell material to suppress coking. By employing the best core-in-shell pellets and supplying a 3:1 mol ratio of steam to CO at 600 °C, more than 97% of the CO was converted to H2 by the WGS reaction and less than 1% was converted to CH4 by a side reaction. Also, none of the CO was converted to coke

A Brief Literature Overview of Various Routes to Biorenewable Fuels from Lipids for the National Alliance for Advanced Biofuels and Bio-products (NAABB) Consortium

Renewable methods of producing transportation fuels are currently the focus of numerous large research efforts across the globe. Renewable fuel produced from algal lipids is one aspect of this research that could have profound implications on future transportation fuel requirements. However, technical challenges remain in several areas of algal-lipid-based fuels. These challenges include the identification and development of robust and productive algal species as well as extraction methods to recover the produced lipids. Not the least of these technical challenges is the conversion of the algae lipids to fungible fuels. This brief literature review focuses primarily on state-of-the-art “downstream” applications of producing fuel from fats and lipids, which can be applied to ongoing research with algae-derived lipids

Optimization of Rhodium-Based Catalysts for Mixed Alcohol Synthesis ? 2012 Progress Report

Pacific Northwest National Laboratory has been conducting research to investigate the feasibility of producing mixed alcohols from biomass-derived synthesis gas (syngas). In recent years, this research has primarily involved the further development of catalysts containing rhodium and manganese based on the results of earlier catalyst screening tests. Testing continued in FY 2012 to further improve the Ir-promoted RhMn catalysts on both silica and carbon supports for producing mixed oxygenates from synthesis gas. This testing re-examined selected alternative silica and carbon supports to follow up on some uncertainties in the results with previous test results. Additional tests were conducted to further optimize the total and relative concentrations of Rh, Mn, and Ir, and to examine selected promoters and promoter combinations based on earlier results. To establish optimum operating conditions, the effects of the process pressure and the feed gas composition also were evaluated

Optimization of Rhodium-Based Catalysts for Mixed Alcohol Synthesis -- 2010 Progress Report

Pacific Northwest National Laboratory has been conducting research for the U.S. Department of Energy, Energy Efficiency Renewable Energy, Biomass Program to investigate the feasibility of producing mixed alcohols from biomass-derived synthesis gas. In recent years this research has primarily involved the further development of a silica-supported catalyst containing rhodium and manganese that was selected from earlier catalyst screening tests. A major effort during 2010 was to examine alternative catalyst supports to determine whether other supports, besides the Davisil 645 silica, would improve performance. Optimization of the Davisil 645 silica-supported catalyst also was continued with respect to candidate promoters iridium, platinum, and gallium, and examination of selected catalyst preparation and activation alternatives for the baseline RhMn/SiO2 catalyst

Study of Tau-pair Production in Photon-Photon Collisions at LEP and Limits on the Anomalous Electromagnetic Moments of the Tau Lepton

Tau-pair production in the process e+e- -> e+e-tau+tau- was studied using data collected by the DELPHI experiment at LEP2 during the years 1997 - 2000. The corresponding integrated luminosity is 650 pb^{-1}. The values of the cross-section obtained are found to be in agreement with QED predictions. Limits on the anomalous magnetic and electric dipole moments of the tau lepton are deduced.Comment: 20 pages, 9 figures, Accepted by Eur. Phys. J.

A Precise Measurement of the Tau Lifetime

The tau lepton lifetime has been measured with the e+e- -> tau+tau- events collected by the DELPHI detector at LEP in the years 1991-1995. Three different methods have been exploited, using both one-prong and three-prong tau decay channels. Two measurements have been made using events in which both taus decay to a single charged particle. Combining these measurements gave tau_tau (1 prong) = 291.8 +/- 2.3 (stat) +/- 1.5 (sys) fs. A third measurement using taus which decayed to three charged particles yielded tau_tau (3 prong) = 288.6 +/- 2.4 (stat) +/- 1.3 (sys) fs. These were combined with previous DELPHI results to measure the tau lifetime, using the full LEP1 data sample, to be tau_tau = 290.9 +/- 1.4 (stat) +/- 1.0 (sys) fs.Comment: 27 pages, 7 figure