**3. Results and discussion**

conditions used for alumina-based catalysts. The TPR profiles were obtained increasing the

Electronic states of Pd, Cl or N were measured using a VG Microtech Multilab equipment following a procedure elsewhere published [19]. The reference-binding energies (BEs) were Al 2p at 74.4 eV and C 1s peak at 284.5 eV for alumina and carbonaceous catalysts, respectively.

The performed reaction test was the selective hydrogenation of 1-heptyne. **Figure 1** shows the scheme of 1-heptyne hydrogenation reaction; the possible products obtained are 1-heptene

A stainless steel reactor was used during the catalytic evaluations. Catalyst of 0.75 g, a hydrogen pressure of 150 kPa and temperatures of 298 and 303 K were used. Seventy-five millilitres of 5% (v/v) 1-heptyne (Fluka, purity of >98%) in toluene (Merck, purity of >99%) solution was used as feed. The possibility of diffusional limitations during the catalytic tests was assessed following a procedure previously described [20]. Experiments were carried out at different stirring velocities in the 180–1400 rpm range. Stirring velocities higher than 500 rpm allowed obtaining identical values of activity and selectivity for all of the catalysts. On the other hand, the catalyst particle size was varied verifying that the conversion and selectivity were the same (within experimental error) than those for the non-crushed catalysts. Therefore, chemical control ensures neither external nor internal diffusional limitations during the

Gas chromatography (GC) using a flame ionization detector (FID) with a capillary column (Chrompack CP WAX 52 CB) was used to analyse 1-heptyne, 1-heptene and n-heptane.

temperature up to 1223 K at 10 K min−1 in a 5% (v/v) hydrogen/argon stream.

18 New Advances in Hydrogenation Processes - Fundamentals and Applications

**2.3. Catalytic evaluations**

catalytic tests.

(desired product) and n-heptane.

**Figure 1.** Scheme for the 1-heptyne hydrogenation.
