Formic acid is a widely used commodity chemical. It can be used as a safe, easily handled, and transported source of hydrogen or carbon monoxide for different reactions, including those producing ...fuels. The review includes historical aspects of formic acid production. It briefly analyzes production based on traditional sources, such as carbon monoxide, methanol, and methane. However, the main emphasis is on the sustainable production of formic acid from biomass and biomass‐derived products through hydrolysis and oxidation processes. New strategies of low‐temperature synthesis from biomass may lead to the utilization of formic acid for the production of fuel additives, such as methanol; upgraded bio‐oil; γ‐valerolactone and its derivatives; and synthesis gas used for the Fischer–Tropsch synthesis of hydrocarbons. Some technological aspects are also considered.
Biomass to fuels: Formic acid is a widely used commodity chemical that can be a source of hydrogen or carbon monoxide. The sustainable production of formic acid from biomass and biomass‐derived products through hydrolysis and oxidation processes is reviewed. New strategies of low‐temperature synthesis from biomass may lead to the utilization of formic acid for the production of fuel additives.
Display omitted
► Non-food biomass can be converted to fuels via thermochemical processes and catalysis. ► Bio-oil obtained by pyrolysis of biomass can be gasified, esterified, hydrotreated or ...cracked by using catalysts. ► Catalysts and chemistry of the bio-oil reactions are considered.
A current aim of society is to produce fuels from non-food biomass and catalysis is central to achieving this aim. Catalytic steam-reforming of biomass gives synthesis gas and this can be further transformed to give transport fuels using catalysis. Biofuels and fuel additives can also be obtained by catalytic upgrading of bio-oil produced by non-catalytic pyrolysis of biomass. This upgrading can be performed by low temperature esterification with alcohols (followed by water separation) or by high temperature gasification, cracking or hydrotreating processes. Upgraded bio-oil can also be obtained by pyrolysis of biomass in the presence of catalysts. This review considers recent trends in the chemistry of these processes for biofuel production and the catalysts used.
Formic acid and formates are often produced by hydrogenation of CO
2
with hydrogen over homogeneous catalysts. The present review reports recent achievements in utilization of heterogeneous ...catalysts. It shows that highly dispersed supported metal catalysts are able to carry out this reaction by providing activation of hydrogen on the metal sites and activation of CO
2
or bicarbonate on the support sites. Important advances have recently been achieved through utilization of catalysts using C
x
N
y
materials as supports. The high activity of these catalysts could be assigned to their ability to stabilize the active metal in a state of single-metal atoms or heterogenized metal complexes, which may demonstrate a higher activity than metal atoms on the surface of metal nanoparticles.
Pt nanoclusters supported on nitrogen-doped carbon nanofibers have shown a considerably improved performance in hydrogen production from formic acid than Pt nanoclusters on undoped carbon nanofibers.
...•Pt catalysts on N-doped carbon nanofibers were studied in HCOOH decomposition.•All catalysts contained a considerable fraction of sub-nm sized Pt clusters.•The N-doped catalysts were about 10 times more active than the undoped catalysts.•They were also more selective and resistant to CO inhibition.•Electron-deficient Pt clusters on the N-doped carbon provided that performance.
The activities of Pt catalysts on carbon nanofibers with different nitrogen contents were compared for hydrogen production by formic acid decomposition. The catalysts contained a fraction of Pt clusters with a mean size of 1.0–2.3nm and possibly a considerable fraction of Pt clusters with a diameter of less than 0.75nm that were invisible by transmission electron microscopy. The activities of N-doped catalysts with low Pt contents (⩽1wt.%) were 10 times higher than the activities of undoped catalysts. The N-doped catalysts demonstrated an improved selectivity to hydrogen and an increased resistance to CO inhibition. However, they were inactive for ethylene hydrogenation. These results are explained by the presence of electron-deficient, two-dimensional sub-nm sized Pt clusters stabilized by pyridinic nitrogen on vacancy sites. In accordance, the Pt-4f7/2 binding energies measured by X-ray photoelectron spectroscopy were 0.6eV higher for the N-doped samples than for the undoped ones.
•Pd catalysts on C, SiO2 and Al2O3 were studied in decomposition of HCOOH vapor.•Potassium carbonate doping led to a considerable improvement of H2 production.•A buffer solution formed in the pores ...of K-doped samples provided this improvement.•Formate ions in the solution were the reaction intermediates decomposing on Pd.
The introduction of potassium carbonate into Pd/Al2O3, Pd/SiO2 and Pd/C catalysts promoted both the catalytic activities and the hydrogen selectivities for the vapor-phase formic acid decomposition, giving values of the turnover frequency (TOF) at 343K that were 8–33 times higher than those for the undoped samples. The apparent activation energies over all the K-doped samples increased considerably, this showing that there is a difference in the reaction path between the doped and the undoped catalysts. Diffuse Reflectance Infrared Fourier Transform Spectroscopy (DRIFTS) has been used to gain an understanding of the nature of the species formed in the Pd/SiO2 catalysts during the reaction. This study showed that a considerable fraction of the HCOOH was condensed in the pores of the catalysts and that the introduction of potassium contributed to the formation of buffer-like solution. The existence of mobile formate ions present in the buffer solution and stabilized by K ions in a K-doped catalyst is an essential factor in the promotion of its activity.
This paper presents a brief review of some research projects carried out in the author’s laboratories over a number of years. The work reported concerns the use of nickel-containing catalysts for a ...range of C
1
reactions: the steam reforming of methane, the methanation of CO, the oxidative coupling of methane and the dry reforming of methane. A number of novel catalysts have been developed in the course of this work, mostly in collaborative projects with industrial organisations, and some of the background to this work is discussed. The paper emphasises the importance in work of the type described of the establishment of contacts between the academic laboratory and industrial researchers such as Mike Spencer.
Female soccer has grown extensively in recent years, however differences in gender-specific physiology have rarely been considered. The female reproductive hormones which rise and fall throughout the ...menstrual cycle, are known to affect numerous cardiovascular, respiratory, thermoregulatory and metabolic parameters, which in turn, may have implications on exercise physiology and soccer performance. Therefore, the main aim of the present study was to investigate potential effects of menstrual cycle phase on performance in soccer specific tests.
Nine sub elite female soccer players, all of whom have menstrual cycles of physiological length; performed a series of physical performance tests (Yo-Yo Intermittent endurance test (Yo-Yo IET), counter movement jump (CMJ) and 3x30 m sprints). These were conducted at distinct time points during two main phases of the menstrual cycle (early follicular phase (FP) and mid luteal phase (LP)) where hormones contrasted at their greatest magnitude.
Yo-Yo IET performance was considerably lower during the mid LP (2833±896 m) as compared to the early FP (3288±800 m). A trend towards significance was observed (p = 0.07) and the magnitude based inferences suggested probabilities of 0/61/39 for superiority/equality/inferiority of performance during the mid LP, leading to the inference of a possibly harmful effect. For CMJ (early FP, 20.0±3.9 cm; mid LP 29.6±3.0 cm, p = 0.33) and sprint (early FP, 4.7±0.1 s; mid LP, 4.7±0.1 s, p = 0.96) performances the results were unclear (8/24/68, 48/0/52, respectively).
The results of this study are in support of a reduction in maximal endurance performance during the mid LP of the menstrual cycle. However, the same effect was not observed for jumping and sprint performance. Therefore, consideration of cycle phase when monitoring a player's endurance capacity may be worthwhile.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Vapour phase decomposition of formic acid has been studied systematically over a range of catalysts: 1.0 and 10
wt.% Pd/C, 0.8
wt.% Au/C and 1.0
wt.% Au/TiO
2. The mean metal particle size of these ...materials was estimated by HRTEM and turnover frequencies were calculated using these data. The Au/C catalyst was the least active and the Pd/C catalysts were the most active for the formic acid decomposition reaction. At about 400
K, these Pd catalysts gave up to 0.04 moles of H
2 per minute per gram of Pd, with a selectivity of 95–99%. The H
2 selectivity for these catalysts was found to be only weakly dependent on the reaction temperature and the formic acid conversion. The Au/TiO
2 catalyst showed only a moderate selectivity to H
2 formation (<70%). The selectivity of this catalyst was improved considerably by the introduction of water vapour. This improvement derived from the high activity of the catalyst for the water–gas shift reaction.
The rate of hydrogen production from vapour-phase formic acid decomposition can be increased by 1-2 orders of magnitude by doping a Pd/C catalyst with potassium ions. Surface potassium formate and/or ...bicarbonate species could be involved in the rate-determining step of this reaction.
PDF
