Showing papers by "National Institute of Advanced Industrial Science and Technology published in 1986"

Rate constants of surface reactions in methanation over Ru/Al2O3 catalyst as determined by pulse surface reaction rate analysis

Abstract: By use of a new PSRA (pulse surface reaction rate analysis) apparatus equipped with an emissionless infrared diffuse reflectance spectrometer (EDR) and a flame ionization detector (FID), the dynamics of both adsorbed CO and produced CH/sub 4/ were simultaneously measured in the CO hydrogenation over Ru/Al/sub 2/O/sub 3/ catalyst. When a CO pulse was introduced to the catalyst via the H/sub 2/ at temperatures above 405 K, an IR absorption band assignable to a linearly adsorbed CO appeared at 2040 cm/sup -1/. At the same time an FID response of CH/sub 4/ quickly increased. It was found that k/sub CH/sub x// is more than 50 times larger than k/sub CO/, indicating that on the Ru/Al/sub 2/O/sub 3/ catalyst the formation of (CH/sub x/)/sub ad/ from adsorbed CO is much slower than its hydrogenation to CH/sub 4/. Furthermore, an H/sub 2/-D/sub 2/ inverse isotope effect was observed for k/sub CO/, suggesting that hydrogen atoms play an important role in the C-O bond dissociation in the CO hydrogenation. A mechanism of the C-O bond dissociation was also discussed on the basis of these results for k/sub CO/. 7 references, 17 figures, 2 tables.

A demiphoneme network representation of speech and automatic labeling techniques for speech data base construction

Abstract: An automatic labeling technique for known speech samples is proposed to construct a fine speech data base for investigating the acoustic-phonetic characteristics of speech. An acoustically compact descriptive unit called Demiphoneme (DPH) is introduced, and a word (or sentence) is represented by a network using DPHs which cover the acoustic variation contained in the utterances of the word (or sentence). An input speech sample is segmented and labeled to the optimal DPH sequence by the following algorithm: (a) Generating possible DPH sequences from an input phoneme sequence by rules. (b) Segmentation of the sample parameter sequence. The resultant segments (called 'SEG's) are the candidates of DPH boundaries. (c) Determining the optimal correspondence between the SEG sequence and each of the DPH sequences generated in (b). (d) Deciding the minimum error DPH sequence and corresponding SEG boundaries. The feasibility of the method is confirmed by applying it to a word set containing 53 city names.

High activity of strong metal–support interaction catalysts for carbon monoxide hydrogenation revealed by pulse surface reaction rate analysis

Abstract: By use of pulse surface reaction rate analysis, it was found that the active sites on titania-supported Pt and Pd catalysts for methanation were much more active in the strong metal–support interaction state than in the normal state.