Steam aging

The CF and GF represent the coke- and gas-forming tendencies of an E-cat compared to a standard steam-aged catalyst sample at the same conversion. The CF and GF are influenced by the type of fresh catalyst and the level of metals deposited on the E-cat. Both the coke and gas factors can be indicative of the dehydrogenation activity of the metals on the catalyst. The addition of amorphous alumina to the catalyst will tend to increase the nonselective cracking, which forms coke and gas. 

The present period is similar to 1900, when gasoline, electric, and steam cars all competed for market share, with the public and the industry unsure of the future. Fifty years from now the fossil fuel era may be seen as a distant memory just like we look at the steam age now. 

The operative concept is essentially based on the relationship between work and energy, and accounts for the reversibility of processes in thermodynamic cycles (in relation to the development of thermal engines in the 19th century, or steam age cf Kittel, 1989). 

Raman Results. Raman spectra of two types of steam-aged (732°C/10h, " 100% steam) sepiolite granules containing 5% V and of several (unsupported) reference vanadates are shown in Figures 3 and 4. 

Figure 2. X-ray diffractogram of Spanish sepiolite after (A) calcination in air at 800°C/lh (B) loading with 5% V and calcination in air at 540°C/10h (C) sample B calcined at 800°C/lh and (D) sample D steam-aged.

Griffith and LesniaT< ( ) have reported that isolated [VoOy] ions are present in Cd V Oy and in aqueous [V Oy] solutions, tuch isolated ions could be e p ected to form in tne steam-aged sepiolite matrix where they would produce an intense band at ca 885 cm with weaker bands at ca 850,cm and 525 cm , see Table I. However, the band at about 1014 cm in the V-loaded sepiolites (observed in the 9 2 6 2 2 7 could result from combination and/or over-... 

Commercial catalysts. Two commercial catalysts made by Katalistiks b.v. were used. The first, EKZ-, was steam aged at 750 C for 18 hrs prior to use and the second, an EKZ-2 equilibrium catalyst from a European refinery, was heated at 300°C in air for 3 hrs prior to use. Alpha alumina, heated at 300 0 in air for 3 hrs, was used in order to estimate the contribution to conversion from thermal cracking. 

Figure 3. X-ray diffractograms of LaHY crystals steam-aged in the presence of (A) 5% and (B) 1.2% vanadium.

Figure 5. Luminescence spectra for vanadyl naphthenate on LaY (A) before and (B) after calcination and (C) steam aging. The excitation wavelength was 300 nm.

For comparison purposes, the spectrum of LaV04 (excited at 330 nm) is given in Fig. 15. The spectra for steam aged LaY crystals containing low (1.29%) V levels is shown in Fig. 16. Luminescent lifetime data are given in Tables I and II. In all cases there are two components, (Tt and a T2), present. The T2 species are very short often exceeding limits of detection. 

Figure 11. Luminescence spectra of tin loaded LaY impregnated with vanadyl porphyrin (A) calcined and (B) steam aged. The excitation wavelength was set at 468 nm.

Figure 14. Luminescence spectra of vanadyl phthalocyanine on steam aged LaY (A) without and (B) with tin addition.

Figure 16. Luminescence emission of steam aged LaY crystals loaded with 1.29% V. The excitation wavelength was 330 nm.

The naphthenate band at 365 nm disappears after steam aging the V-loaded (1.29%) catalysts and a broad band in the 450-575 nm region is formed, Fig 5C both V205 and LaV04 exhibit spectral bands in this region. In the present study, V205 formation has been ascertained by taking the luminescence spectrum at 77 K. 

The presence of V205 (together with EuV04) has also been observed by Anderson et al (29) after steam-aging vanadyl naphthenate on EuY crystals. Roozenboom... 

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