TPSR analyses

Figure 29.8 TPSR analyses of CsHg+CO2 + He (a) on Ce02 and (b) on Ceo.8Feo 202 Total flow 110 ml/min C3Hg/C02 ratio = 1.

During TPSR, the rate of gasification of the carbon deposit (as determined by continuous measurement of the effluent gas composition) was recorded as a function If time. The data are represented by the calculated gas production rate versus bed temperature as In conventional thermal analysis. TPSR analysis was performed for various conditions of exposure temperature, exposure duration, and exposure gas (CO, or C2H2) for both 1-... 

Isopropanol adsorption (at 40 C) and TPSR analysis was performed on the fully hydrated acid and after in situ calcination at 70, 115, and 320°C in order to obtain more insights on the role of the degree of hydration on the catalytic activity of the phospho-tungstic Wells-Dawson type acid. 

The TPSR analysis, after saturation of the fully hydrated acid with successive pulses of isopropanol, showed the desorption of molecular alcohol at 77°C, propylene at 107°C, CO with three maxima at 120, 177, and 334°C, and water. The analysis after dehydration at 70, 115, and 320" C is similar although no CO was detected. The desorption of molecular isopropanol only on the hydrated acid (no molecular alcohol desorbs upon complete dehydration at 400°C) indicated that the alcohol dissolves in an aqueous layer surrounding the primary structure of the P2WigOg2 heteropoly anion. 

Calcination Temperatures, Degree of Hydration, Amount of Methanol Molecularly Absorbed, Amount of Propylene produced during TPSR Analysis and Temperature of Surface Reaction of Isopropoxy Species towards... 

Amount of molecular isopropanol desorbed during TPSR analysis per unit weight of Wells-Dawson acid with the corresponding degree of hydration (H6P2Wig062-xH20). 

The second part of this work will be dedicated to the start of the game what are the pieces motions How can the adsorbed molecules react on the surface and among all the playground, where does the real action take place This is the so-called in situ approach for which techniques such as temperature-programmed surface reaction (TPSR) or transient analysis by pulse injection have been developed. 

This chapter reports the results from transient experiments (mainly, TPD or TPSR) coupled with on-line analysis of reaction mixture at the outlet of a well-stirred reactor. It means that the gas composition detected at the outlet of the reactor is in contact with the catalyst inside the reactor. Catalytic runs in isothermal conditions were also proceeded in order to avoid strong adsorptions of reactants or intermediates. 

Figure 5.11. TPSR DeNO reaction over CeZr02 (200ppm NO, lOOOppm CH3OH, 9% 02). GC/MS analysis at 225°C as indicated on Figure 5.7 [32],...

NO was stored on the catalyst surface under controlled conditions at 350°C (see Section 1 in Chapter 3) then the catalyst regeneration was performed at constant temperature by step addition of H2 (TRM), by thermal decomposition in He (TPD) and by heating in flowing H2 (TPSR). This allowed the analysis of the thermal stability/reactivity of the stored nitrates. 

Although, this method is questionable to measure the density of surface active sites when the reactants are not NO-NH3, th e is no doubt that this technique is the right choice to investigate the surface of those materials active on selective catalytic reduction (SCR) of nitric oxide with ammonia. In fact, 10 years later, Dumesic and coworkers [12,13] upgraded the use of NO-NH3 as probe molecules in their investigation of a series of supported vanadium on titania catalysts during DeNO c process. The authors performed TPSR (online mass spectrometric analysis of desorbed products upon heating) and in situ infrared (IR) analysis over the catalysts with preadsorbed ammonia exposed to either NO, O2, or NO + O2 mixture. 

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