Reaction routes for methane conversion on transition metals at low temperature

Two new metal catalysed routes for methane conversion are discussed: methane oligomerization and methane addition to olefins. These reactions are realized in a reaction cycle consisting of several steps. In both reaction sequences methane is first dissociatively adsorbed on a reduced transition metal catalyst between 500 and 800 K resulting in surface carbon and hydrogen. A particular highly reactive surface carbonaceous intermediate is found to produce C2+ hydrocarbons upon hydrogenation between 300 and 400 K. The maximum yield for higher hydrocarbons is 13% obtained on a Ru/SiO2 catalyst. When olefins are co-adsorbed together with surface carbon generated from methane, more C2+ hydrocarbons are produced. Experiments with 13C labelled CH4 and unlabelled olefins demonstrate that surface carbon from methane is incorporated into the co-adsorbed olefins

Hydrocarbon production

Hydrocarbons are obtained by contacting a hydrogen containing moiety with a catalytically active support containing carbonaceous material deposited thereon wherein the carbonaceous material is obtainable by subjecting methane to a decomposition treatment in the presence of said support at a temperature not exceeding 600 DEG C. Moiety source is e.g. a hydrogen stream from a refinery or can be molecular H2. Support may be of SiO2, Al2O3 or their mixture and may also contain Ru, Ir, Rh, Ni etc. as the catalyst

Promotion by vanadium compound of the elementary reaction steps in the synthesis gas reaction catalyzed by rhodium

In order to understand the promoting effect of V compd. on Rh catalysts in synthesis gas conversion, changes in reaction rates of elementary steps and the surface concn. of intermediates have been monitored. V promotion enhances the rate of CO dissocn. which is the most important effect. Reactive surface carbon is stabilized by V which results in a slightly decreased reactivity in methane formation. Transient expts. using isotopes and GCMS detection show that CO insertion is not promoted by V. The hydrogenation of ethanal to ethanol is enhanced by V while the desorption rate of ethanal is decrease

Executive Functioning in Daily Life in Parkinson's Disease: Initiative, Planning and Multi-Task Performance

Impairments in executive functioning are frequently observed in Parkinson's disease (PD). However, executive functioning needed in daily life is difficult to measure. Considering this difficulty the Cognitive Effort Test (CET) was recently developed. In this multi-task test the goals are specified but participants are free in their approach. This study applies the CET in PD patients and investigates whether initiative, planning and multi-tasking are associated with aspects of executive functions and psychomotor speed. Thirty-six PD patients with a mild to moderate disease severity and thirty-four healthy participants were included in this study. PD patients planned and demonstrated more sequential task execution, which was associated with a decreased psychomotor speed. Furthermore, patients with a moderate PD planned to execute fewer tasks at the same time than patients with a mild PD. No differences were found between these groups for multi-tasking. In conclusion, PD patients planned and executed the tasks of the CET sequentially rather than in parallel presumably reflecting a compensation strategy for a decreased psychomotor speed. Furthermore, patients with moderate PD appeared to take their impairments into consideration when planning how to engage the tasks of the test. This compensation could not be detected in patients with mild PD

Reference Data for the Ruff Figural Fluency Test Stratified by Age and Educational Level

The Ruff Figural Fluency Test (RFFT) was developed to avoid the difficulties that were encountered in earlier tests of figural fluency. Although the test characteristics of the RFFT seem to be good and it is a valuable addition to neuropsychological assessments, reference data are still scarce. To this aim, we required 2,404 community dwelling persons in Groningen, the Netherlands to perform the RFFT. All 1,651 persons with a complete RFFT and known educational level formed the reference sample. Their age ranged from 35 to 82 years and their educational level from primary school to university grade. Ninety-six percent of the persons were of Western European descent. All tests were analyzed by two independent examiners and subsequently three measures were calculated: number of unique designs, number of perseverative errors and error ratio. The main finding was that performance on the RFFT was dependent on age and educational level. This was not only observed in older persons but also in young and middle-aged persons. Reference data for the three RFFT measures are presented in groups of five years of age ranging from 35–39 years to 75 years or older