Revealing Electronic Influences in the Semihydrogenation of Acetylene

Abstract

The electronic influence on the catalytic properties in the semihydrogenation of acetylene is addressed by applying unsupported intermetallic materials from the solid solution Ga 1−x Sn x Pd 2 (0 ≤ x ≤ 1). Due to the only marginal changes in the crystal structure, the whole series shows excellent selectivity to ethylene (∼85%) comparable with the binary GaPd 2 . Moreover, the incremental addition of up to one electron per formula unit reveals a maximum in the specific catalytic activity around the nominal composition with x = 0.28 corresponding to 4.0 atom % tin in the near-surface region, as revealed by operando X-ray photoelectron spectroscopy measurements. The study shows a reliable and quantitative relation between the d-band shift and catalytic activity, revealing once more the potential of intermetallic compounds in heterogeneous catalysis.

The ternary systems Al–Ga–Pd and Ga–Sb–Pd. Search for new catalytic materials

“…5). In addition, the observed activity is comparable with the most active sample of the solid solution Ga 1-x Sn x Pd 2 [2]. These findings correlate with the geometric and electronic models for semi-hydrogenation of acetylene [34].…”

“…Taking into account the properties of GaPd 2 [1] and Ga 1-x Sn x Pd 2 [2], the solid solution Ga 1-x Sb x Pd 2 (sample with nominal composition Ga 28.3 Sb 5 Pd 66.7 ) was chosen to test its catalytic properties in the semihydrogenation of acetylene.…”

“…The catalytic properties of Ga-Pd intermetallic compounds [1] and recent investigations of Ga-Sn-Pd phases [2,3] make the ternary systems of gallium with metals/semimetals of the groups 13-15 of the periodic table (M) and platinum metals (T) attractive for the search for new catalytic materials. The systems Ga-M-T have not been thoroughly investigated (Table 1, [4]).…”

Intermetallic compounds in catalysis – a versatile class of materials meets interesting challenges

“…Intermetallic compounds have been applied in an unsupported and supported state to systematically investigate ligand and geometric effects as well as the influence of the support – in recent years especially in the semi-hydrogenation of acetylene [ 35 , 36 ], methanol synthesis [ 37 ] and methanol steam reforming [ 38 ]. Due to their electrical conductivity, intermetallic compounds are also applicable in the field of electrocatalysis, enhancing the combined experimental and quantum chemical approach summarised by Jaramillo et al [ 39 ] Controlled leaching [ 40 ] and development of electrodes with higher stability [ 41 ] based on the Brewer-Engel bonding theory [ 42 ] are just two examples.…”

Corrosion‐Free EMF Measurements of Zinc‐Based Intermetallic Compounds at Ambient Temperature

“…[4] The above-mentioned characteristic properties of intermetallic compounds ensure a reproducibility of defined surface structures and thus a direct correlation between the catalytic behavior and the crystal and/or electronic structure of an intermetallic compound. [5] The formation of partially very broad homogeneity ranges of the intermetallic compounds (realized by substitution, filling of interstitial spaces of the surplus type of atom or by voids of the subordinate type of atom) also offer the possibility of changing the electronic structure of an intermetallic compound while largely retaining the geometric structure, whereby a separate analysis of the influence by changing the electronic structure of an intermetallic compound becomes accessible. The enormous potential of intermetallic compounds for knowledge-based catalysis research is illustrated by examples such as the development of non-precious metal catalyst materials for the semi-hydrogenation of acetylene, [6] the development of stable and highly active catalysts for methanol steam reforming (MSR) [7] as well as their broad use in electrocatalysis.…”