Rapid, non-invasive characterization of the dispersity of emulsions via microwaves

A rapid and non-invasive method to determine the dispersity of emulsions is developed based on the interrelationship between the droplet size distribution and the dielectric properties of emulsions. A range of water-in-oil emulsions with different water contents and droplet size distributions were analysed using a microwave cavity perturbation technique together with dynamic light scattering. The results demonstrate that the dielectric properties, as measured by non-invasive microwave cavity analysis, can be used to characterise the dispersity of emulsions, and is also capable of characterizing heavy oil emulsions. This technique has great potential for industrial applications to examine the sedimentation, creaming and hence the stability of emulsions

The decarbonization of coal tar via microwave-initiated catalytic deep dehydrogenation

Coal tar, a major by-product of the coal industry, presents considerable difficulties in its refining and conversion into fuels due to its complex chemical composition and physical properties, such as high viscosity, corrosiveness, thermal instability, etc. Here we report a new route for producing hydrogen-rich gases together with carbonaceous materials, including carbon nanotubes, through the microwave-initiated catalytic deep dehydrogenation of coal tar using inexpensive iron catalysts. The resulting carbonaceous materials generated over the catalyst were investigated using a variety of techniques including scanning electron microscopy (SEM), transmission electron microscopy (TEM), temperature programmed oxidation (TPO) and Raman spectroscopy. Importantly, we have found that an aqueous emulsion feed of the coal tar enables considerably easier handling and an enhanced hydrogen production whilst also significantly reducing the extent of catalyst deactivation. This behaviour is shown to be assisted by the phenomenon of micro-explosion that enhances mass and heat transfer during the catalytic reactions

The decarbonisation of petroleum and other fossil hydrocarbon fuels for the facile production and safe storage of hydrogen

The importance of extracted and refined fossil carbonaceous fuels (petroleum, diesel etc.) to the development of human society cannot be overestimated. These natural resources have improved billions of lives, worldwide, in providing accessible, relatively inexpensive energy at nearly every scale. Notwithstanding the credible advances in renewable energy production over the past decade or so, the aerial combustion of coal, natural gas and liquid fossil fuels, given humankinds insatiable demand for power, will continue to be the ready source of more than 85% of the world's energy in the foreseeable and possibly the distant future. Human activities based on the combustion of fossil fuels, however, has led to significant anthropogenic emissions of carbon dioxide (CO2) to the atmosphere – and that fact is now seen as the major contributor to global warming and climate change. To stabilise global mean temperatures will depend on the ultimate transformation of humankind's energy system to one that does not introduce CO2 into the atmosphere. The hydrogen economy has long been mooted as a route to achieving the required net-zero emissions energy future. Paradoxically, fossil fuel sources such as petroleum, crude and extra-heavy crude oil, petrol, diesel and methane are reported here to produce high volumes of high-purity hydrogen through their microwave-initiated catalytic dehydrogenation using fine iron particles. The co-product of this dehydrogenation process, solid carbon, can be safely stored underground in perpetuity or converted in future to valuable hydrocarbons and other materials. Through their catalytic dehydrogenation to yield carbon-free hydrogen – rather than through their aerial combustion to produce carbon dioxide – petroleum and other fossil fuels can now serve as an energy pathway to stabilising global mean temperatures

Transforming carbon dioxide into jet fuel using an organic combustion-synthesized Fe-Mn-K catalyst

Funder: King Abdulaziz City for Science and Technology (KACST); doi: https://doi.org/10.13039/501100004919Abstract: With mounting concerns over climate change, the utilisation or conversion of carbon dioxide into sustainable, synthetic hydrocarbons fuels, most notably for transportation purposes, continues to attract worldwide interest. This is particularly true in the search for sustainable or renewable aviation fuels. These offer considerable potential since, instead of consuming fossil crude oil, the fuels are produced from carbon dioxide using sustainable renewable hydrogen and energy. We report here a synthetic protocol to the fixation of carbon dioxide by converting it directly into aviation jet fuel using novel, inexpensive iron-based catalysts. We prepare the Fe-Mn-K catalyst by the so-called Organic Combustion Method, and the catalyst shows a carbon dioxide conversion through hydrogenation to hydrocarbons in the aviation jet fuel range of 38.2%, with a yield of 17.2%, and a selectivity of 47.8%, and with an attendant low carbon monoxide (5.6%) and methane selectivity (10.4%). The conversion reaction also produces light olefins ethylene, propylene, and butenes, totalling a yield of 8.7%, which are important raw materials for the petrochemical industry and are presently also only obtained from fossil crude oil. As this carbon dioxide is extracted from air, and re-emitted from jet fuels when combusted in flight, the overall effect is a carbon-neutral fuel. This contrasts with jet fuels produced from hydrocarbon fossil sources where the combustion process unlocks the fossil carbon and places it into the atmosphere, in longevity, as aerial carbon - carbon dioxide

Transforming carbon dioxide into jet fuel using an organic combustion-synthesized Fe-Mn-K catalyst.

Funder: King Abdulaziz City for Science and Technology (KACST); doi: https://doi.org/10.13039/501100004919With mounting concerns over climate change, the utilisation or conversion of carbon dioxide into sustainable, synthetic hydrocarbons fuels, most notably for transportation purposes, continues to attract worldwide interest. This is particularly true in the search for sustainable or renewable aviation fuels. These offer considerable potential since, instead of consuming fossil crude oil, the fuels are produced from carbon dioxide using sustainable renewable hydrogen and energy. We report here a synthetic protocol to the fixation of carbon dioxide by converting it directly into aviation jet fuel using novel, inexpensive iron-based catalysts. We prepare the Fe-Mn-K catalyst by the so-called Organic Combustion Method, and the catalyst shows a carbon dioxide conversion through hydrogenation to hydrocarbons in the aviation jet fuel range of 38.2%, with a yield of 17.2%, and a selectivity of 47.8%, and with an attendant low carbon monoxide (5.6%) and methane selectivity (10.4%). The conversion reaction also produces light olefins ethylene, propylene, and butenes, totalling a yield of 8.7%, which are important raw materials for the petrochemical industry and are presently also only obtained from fossil crude oil. As this carbon dioxide is extracted from air, and re-emitted from jet fuels when combusted in flight, the overall effect is a carbon-neutral fuel. This contrasts with jet fuels produced from hydrocarbon fossil sources where the combustion process unlocks the fossil carbon and places it into the atmosphere, in longevity, as aerial carbon - carbon dioxide

Effect of Minor Co Substitution for Fe on the Formability and Magnetic and Magnetocaloric Properties of the Amorphous Fe₈₈Ce₇B₅ Alloy

A small amount of Co was added to the Fe88Ce7B5 glass forming alloy for the possibility of improving its glass formability and magnetocaloric effect. The Curie temperature of the amorphous Fe88-xCe7B5Cox (x = 0, 1, 2, 3) ribbons increases linearly with the Co content, while the maximum magnetic entropy change (−ΔSmpeak) increases to 3.89 J/(kg × K) under 5 T at x = 1 and subsequently decreases with further Co addition. The mechanism for the influence of Co addition on magnetic properties and the magnetocaloric effect of the amorphous alloys was investigated. Furthermore, a flattened −ΔSm profile was designed in the amorphous laminate composed of the amorphous Fe88-xCe7B5Cox (x = 0, 1, 2) ribbons. The high average −ΔSm from ~287 K to ~320 K indicates the potential application perspective of the amorphous hybrid as a magnetic refrigerant of a domestic refrigerator

Effect of Minor Co Substitution for Fe on the Formability and Magnetic and Magnetocaloric Properties of the Amorphous Fe88Ce7B5 Alloy

A small amount of Co was added to the Fe88Ce7B5 glass forming alloy for the possibility of improving its glass formability and magnetocaloric effect. The Curie temperature of the amorphous Fe88-xCe7B5Cox (x = 0, 1, 2, 3) ribbons increases linearly with the Co content, while the maximum magnetic entropy change (−ΔSmpeak) increases to 3.89 J/(kg × K) under 5 T at x = 1 and subsequently decreases with further Co addition. The mechanism for the influence of Co addition on magnetic properties and the magnetocaloric effect of the amorphous alloys was investigated. Furthermore, a flattened −ΔSm profile was designed in the amorphous laminate composed of the amorphous Fe88-xCe7B5Cox (x = 0, 1, 2) ribbons. The high average −ΔSm from ~287 K to ~320 K indicates the potential application perspective of the amorphous hybrid as a magnetic refrigerant of a domestic refrigerator

Metals and non-metals in the periodic table

The demarcation of the chemical elements into metals and non-metals dates back to the dawn of Dmitri Mendeleev's construction of the periodic table; it still represents the cornerstone of our view of modern chemistry. In this contribution, a particular emphasis will be attached to the question ‘Why do the chemical elements of the periodic table exist either as metals or non-metals under ambient conditions?’ This is perhaps most apparent in the p-block of the periodic table where one sees an almost-diagonal line separating metals and non-metals. The first searching, quantum-mechanical considerations of this question were put forward by Hund in 1934. Interestingly, the very first discussion of the problem—in fact, a pre-quantum-mechanical approach—was made earlier, by Goldhammer in 1913 and Herzfeld in 1927. Their simple rationalization, in terms of atomic properties which confer metallic or non-metallic status to elements across the periodic table, leads to what is commonly called the Goldhammer–Herzfeld criterion for metallization. For a variety of undoubtedly complex reasons, the Goldhammer–Herzfeld theory lay dormant for close to half a century. However, since that time the criterion has been repeatedly applied, with great success, to many systems and materials exhibiting non-metal to metal transitions in order to predict, and understand, the precise conditions for metallization. Here, we review the application of Goldhammer–Herzfeld theory to the question of the metallic versus non-metallic status of chemical elements within the periodic system. A link between that theory and the work of Sir Nevill Mott on the metal-non-metal transition is also highlighted. The application of the ‘simple’, but highly effective Goldhammer–Herzfeld and Mott criteria, reveal when a chemical element of the periodic table will behave as a metal, and when it will behave as a non-metal. The success of these different, but converging approaches, lends weight to the idea of a simple, universal criterion for rationalizing the instantly-recognizable structure of the periodic table where …the metals are here, the non-metals are there … The challenge of the metallic and non-metallic states of oxides is also briefly introduced

Decarbonisation of fossil fuels: Microwave-promoted deep catalytic dehydrogenation of liquid alkanes

Hydrogen as an energy carrier promises a sustainable energy revolution. However, one of the greatest challenges for any future hydrogen economy is the necessity for large scale hydrogen storage and prodn. not involving concurrent CO2 prodn. The high intrinsic hydrogen content of liq.-​range alkane hydrocarbons (including diesel) offers a route to CO2-​free hydrogen prodn. through their catalytic deep dehydrogenation. We report here a means of rapidly liberating high-​purity hydrogen by microwave-​promoted catalytic dehydrogenation of liq. alkanes using Fe and Ni particles supported on silicon carbide. H2 prodn. selectivity from all evolved gases of some 98​%, is achieved with less than a fraction of a percent of adventitious CO and CO2. The major co-​product is solid, elemental carbon