The selectivity towards 1,4-butynediol hydrogenation
of both a
standard 5 wt % Pt on graphite supported catalyst and a biogenic Pt
analogue is reported. In both cases, it is determined using cyclic
voltammetry that step sites afford the greatest extent of hydrogenation
and that deliberate blocking of such sites gives rise to significant
selectivity in favor of the 1,4-butenediol product. For the 5 wt %
Pt/graphite catalyst, irreversible adsorption of bismuth was used
as the step site blocking agent. In the case of the biogenic Pt nanoparticles
(NPs) synthesized within the bacterium Escherichia coli, residual molecular organic fragments, left over after chemical
cleaning and subsequent separation from the bacterial support, were
observed to have accumulated preferentially at defect sites. This
phenomenon facilitated an increase in selectivity toward alkenic products
of up to 1.4 during hydrogenation of the alkyne. When biogenic NPs
of platinum supported upon bacterial biomass were also investigated,
they too were found to be active and selective although selectivity
toward 1,4-butenediol was optimized only after the particles were
chemically cleaned and separated from the biomass. Bi-poisoned 5%
Pt on graphite, although highly selective, gave half the reaction
rate of the biogenic counterpart (20% and 45% conversion of starting
material respectively after 2 h), but the latter exhibited less selectivity
for butenediol (0.7 and 0.9 respectively). It is proposed therefore
that such biogenic materials may potentially act in a similar manner
to Lindlar-type catalysts, used extensively in organic synthesis for
selective hydrogenation of alkynes, in which an additive partially
poisons metal sites but without the associated hazards of toxic heavy
metals such as lead being present.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.