46 research outputs found
Discovering indium as hydrogen production booster for a Cu/SiO2 catalyst in steam reforming of methanol
We report on the use of In as an effective H2 production promoter in a Cu/SiO2 catalyst for the steam reforming of methanol. To date, In promotion has been limited to noble metals because of its tendency to âburyâ other metals thus compromising the catalytic activity. Here, we prepared a silica-supported Cu-In catalyst via a urea-assisted co-precipitation method that showed a higher H2 productivity compared to the monometallic catalyst and a remarkable H2/CO2 molar ratio of almost 3 at 220 °C. Through XPS, XRPD and HRTEM-EDX along with H2- and CO-TPR, H2O-TPD, and N2O titrations, supported by computational modeling, we attributed such superior performances to an easier H2O activation due to improved electronic properties of the Cu phase, that is, its lower oxidation state via electron density transfer from the InOx buffer phase as a 1D ânecklaceâ structures crucially mediating the interaction of small Cu nanoparticles (2.6 nm) and silica
Ruthenium on Carbonaceous Materials for the Selective Hydrogenation of HMF
We report the use of Ru catalysts supported in the activated carbon (AC) and carbon nanofibers (CNFs) for the selective production of liquid fuel dimethylfuran (DMF) and fuel additives alkoxymethyl furfurals (AMF). Parameters such as the reaction temperature and hydrogen pressure were firstly investigated in order to optimise the synthesis of the desired products. Simply by using a different support, the selectivity of the reaction drastically changed. DMF was produced with AC as support, while a high amount of AMF was produced when CNFs were employed. Moreover, the reusability of the catalysts was tested and deactivation phenomena were identified and properly addressed. Further studies need to be performed in order to optimise the stability of the catalysts
The selectivity, voltage-dependence and acid sensitivity of the tandem pore potassium channel TASK-1 : contributions of the pore domains
We have investigated the contribution to ionic
selectivity of residues in the selectivity filter and pore
helices of the P1 and P2 domains in the acid sensitive
potassium channel TASK-1. We used site directed mutagenesis
and electrophysiological studies, assisted by structural
models built through computational methods. We have
measured selectivity in channels expressed in Xenopus
oocytes, using voltage clamp to measure shifts in reversal
potential and current amplitudes when Rb+ or Na+ replaced
extracellular K+. Both P1 and P2 contribute to selectivity,
and most mutations, including mutation of residues in the
triplets GYG and GFG in P1 and P2, made channels nonselective.
We interpret the effects of theseâand of other
mutationsâin terms of the way the pore is likely to be
stabilised structurally. We show also that residues in the
outer pore mouth contribute to selectivity in TASK-1.
Mutations resulting in loss of selectivity (e.g. I94S, G95A)
were associated with slowing of the response of channels to
depolarisation. More important physiologically, pH sensitivity
is also lost or altered by such mutations. Mutations
that retained selectivity (e.g. I94L, I94V) also retained their
response to acidification. It is likely that responses both to
voltage and pH changes involve gating at the selectivity filter
Search for Decay in LSND
We observe a net beam-excess of (stat) (syst) events,
above 160 MeV, resulting from the charged-current reaction of
and/or on C and H in the LSND detector. No beam related muon
background is expected in this energy regime. Within an analysis framework of
, we set a direct upper limit for this
branching ratio of at 90% confidence level.Comment: 4 pages, 4 figure