Search

This multi-disciplinary paper aims to provide a roadmap for the development of an integrated, process-intensified technology for the production of H2, NH3 and NH3-based symbiotic/smart fertilizers (referred to as target products) from renewable feedstock with CO2 sequestration and utilization while addressing environmental issues relating to the emerging Food, Energy and Water shortages as a result of global warming. The paper also discloses several novel processes, reactors and catalysts. In addition to the process intensification character of the processes used and reactors designed in this study, they also deliver novel or superior products so as to lower both capital and processing costs. The critical elements of the proposed technology in the sustainable production of the target products are examined under three-sections: (1) Materials: They include natural or synthetic porous water absorbents for NH3 sequestration and symbiotic and smart fertilizers (S-fertilizers), synthesis of plasma interactive supported catalysts including supported piezoelectric catalysts, supported high-entropy catalysts, plasma generating-chemical looping and natural catalysts and catalysts based on quantum effects in plasma. Their performance in NH3 synthesis and CO2 conversion to CO as well as the direct conversion of syngas to NH3 and NH3—fertilizers are evaluated, and their mechanisms investigated. The plasma-generating chemical-looping catalysts (Catalysts, 2020, 10, 152; and 2016, 6, 80) were further modified to obtain a highly active piezoelectric catalyst with high levels of chemical and morphological heterogeneity. In particular, the mechanism of structure formation in the catalysts BaTi1−rMrO3−x−y{#}xNz and M3O4−x−y{#}xNz/Si = X was studied. Here, z = 2y/3, {#} represents an oxygen vacancy and M is a transition metal catalyst. (2) Intensified processes: They include, multi-oxidant (air, oxygen, CO2 and water) fueled catalytic biomass/waste gasification for the generation of hydrogen-enriched syngas (H2, CO, CO2, CH4, N2); plasma enhanced syngas cleaning with ca. 99% tar removal; direct syngas-to-NH3 based fertilizer conversion using catalytic plasma with CO2 sequestration and microwave energized packed bed flow reactors with in situ reactive separation; CO2 conversion to CO with BaTiO3−x{#}x or biochar to achieve in situ O2 sequestration leading to higher CO2 conversion, biochar upgrading for agricultural applications; NH3 sequestration with CO2 and urea synthesis. (3) Reactors: Several patented process-intensified novel reactors were described and utilized. They are all based on the Multi-Reaction Zone Reactor (M-RZR) concept and include, a multi-oxidant gasifier, syngas cleaning reactor, NH3 and fertilizer production reactors with in situ NH3 sequestration with mineral acids or CO2. The approach adopted for the design of the critical reactors is to use the critical materials (including natural catalysts and soil additives) in order to enhance intensified H2 and NH3 production. Ultimately, they become an essential part of the S-fertilizer system, providing efficient fertilizer use and enhanced crop yield, especially under water and nutrient stress. These critical processes and reactors are based on a process intensification philosophy where critical materials are utilized in the acceleration of the reactions including NH3 production and carbon dioxide reduction. When compared with the current NH3 production technology (Haber–Bosch process), the proposed technology achieves higher ammonia conversion at much lower temperatures and atmospheric pressure while eliminating the costly NH3 separation process through in situ reactive separation, which results in the production of S-fertilizers or H2 or urea precursor (ammonium carbamate). As such, the cost of NH3-based S-fertilizers can become competitive with small-scale distributed production platforms compared with the Haber–Bosch fertilizers. [ABSTRACT FROM AUTHOR]

The Fischer-Tropsch synthesis (FTS) for the conversion of carbon monoxide and hydrogen to higher hydrocarbons was investigated over a supported Cu/Co catalyst promoted by dielectric-barrier discharges (DBDs) at relatively low temperatures and ambient pressure. The effect of plasma power, operation pressure, and H2/CO molar ratio on the activity and selectivity of the catalyst in a DBD reactor were studied. The fresh and used catalyst samples were characterized by scanning electron microscopy, transmission electron microscopy, energy dispersive X-ray, and X-ray diffraction. We also used DBDs in catalyst preparation as a technique to enhance metal distribution on the catalyst support. The present study reveals that plasma can promote the FTS over a Cu/Co-based catalyst at low temperatures and ambient pressure. The formation of methane was strongly suppressed in plasma. In contrast to conventional FTS, CO conversion was higher at low operating pressure than that at higher pressure in the DBD-promoted FTS, which indicates the presence of a new reaction path for FTS.

A new application of agro-process intensification is described for nitrogen fixation by Azospirillum brasilense supported within the pores of sulphonated-neutralised polyHIPE polymers (PHPs) which are highly hydrophilic, elastic, crosslinked and ionic with nano-structured pore walls. These bioactive macroscopic polymer particles, when used as soil additives act as micro-bioreactors within the soil and facilitate the interactions between plant roots, root exudates, water, nutrients and bacteria (reactive components), because plant roots penetrate into these micro-bioreactors which simultaneously absorb water and nutrients while generating biofertiliser through the nitrogen fixing bacteria within them. Hence, these soil additives act as synthetic rhizosphere (SRS). In greenhouse experiments, it is shown that the presence of the bioactive SRS at 0.5 wt% level in the soil without any fertiliser addition increases the dry grass shoots by 9.6%, 9.5%, 40% and 145% after 3, 6, 9 and 12 weeks of growth, respectively, compared to grass grown with no SRS or bacteria. Progressive yield enhancement with Azospirillum brasilense supported on PHPs is due to reduction of soil nutrients thus switching nitrogen fixing bacterium from consumption to production of nitrogen. The environmental impact and sustainability of SRS media are also considered and compared with other soil additives: super absorbent polymers and biochar.

Reprocessing of spent nuclear fuel for the recovery of the fissionable materials (mainly uranium and plutonium), is performed by solvent extraction. Thermal oxide reprocessing (THORP) is the most widely used technique in which processing fluids gradually degrade and form stable emulsions that are referred to as interfacial crud (IFC). IFC is highly viscous and stable and its deposition in the nuclear reprocessing circuit results in blockages and plant shut-down for the recovery of IFC and cleaning of the lines. IFC is also encountered in other non-nuclear extraction processes such as crude oil production from oil wells due to the presence of naturally occurring surface active species in crude oil. In this study, we first investigated the synthesis of a non-radioactive IFC simulants and subsequently examined its demulsification behavior (separation into oil and aqueous components). It was concluded that the IFC is stabilized by surface active species, the removal of which results in the demulsification and subsequent phase separation and the prevention of the IFC re-formation. Demulsification was carried out using sulfonated, micro-porous, crossed-linked materials known as PolyHIPE Polymers (PHP). Demulsification characteristic of the hydrophilic PHP is unique compared with other demulsifiers, since the capture of surface active species is largely irreversible and hence, demulsified IFC does not reform upon mixing of the oil and aqueous phases. It is therefore possible to remove surface active species from the reaction circuit continuously.

The characteristics of powder coatings manufactured through a novel processing technique based on nonisothermal Nlow-induced phase inversion granulation enhanced by fluid injection to promote phase inversion and particle formation from melt state is summarized. Experiments were carried out in a purpose-built granulator, which operates in a parallel disk rotor-stator arrangement, so that the mechanism of granulation could be studied. The product of this intensive granulation was compared with that of the conventional powder coating manufacturing process. Understanding the mechanism of intensive granulation helped to redesign the equipment that resulted in smaller particles. Pigment dispersion characteristics were improved by intensive granulation. Also, the particle size span can be significantly reduced by dry granulation and gas-phase granulation, and the flowability can be improved by wet granulation. Chemical analysis of particles by Fourier transform infrared spectroscopic analysis showed that the injection of coolant fluid had no effect on the chemical composition. © 2011 American Institute of Chemical Engineers AIChE J, 2012 [ABSTRACT FROM AUTHOR]

Simultaneous generation of plasma by microwave irradiation of perovskite or the spinel type of silica supported porous catalyst oxides and their reduction by nitrogen in the presence of oxygen is demonstrated. As a result of plasma generation in air, NOx generation is accompanied by the development of highly heterogeneous regions in terms of chemical and morphological variations within the catalyst. Regions of almost completely reduced catalyst are dispersed within the catalyst oxide, across micron-scale domains. The quantification of the catalyst heterogeneity and evaluation of catalyst structure are studied using Scanning Electron Microscopy, Energy Dispersive X-ray Spectroscopy and XRD. Plasma generating supported spinel catalysts are synthesized using the technique developed by the author (Catalysts; 2016; 6; 80) and BaTiO3 is used to exemplify perovskites. Silica supported catalyst systems are represented as M/Si = X (single catalysts) or as M(1)/M(2)/Si = X/Y/Z (binary catalysts) where M; M(1) M(2) = Cr; Mn; Fe; Co; Cu and X, Y, Z are the molar ratio of the catalysts and SiO2 support. Composite porous catalysts are synthesized using a mixture of Co and BaTiO3. In all the catalysts, structural heterogeneity manifests itself through defects, phase separation and increased porosity resulting in the creation of the high activity sites. The chemical heterogeneity results in reduced and oxidized domains and in very large changes in catalyst/support ratio. High electrical potential activity within BaTiO3 particles is observed through the formation of electrical treeing. Plasma generation starts as soon as the supported catalyst is synthesized. Two conditions for plasma generation are observed: Metal/Silica molar ratio should be > 1/2 and the resulting oxide should be spinel type; represented as MaOb (a = 3; b = 4 for single catalyst). Composite catalysts are represented as {M/Si = X}/BaTiO3 and obtained from the catalyst/silica precursor fluid with BaTiO3 particles which undergo fragmentation during microwave irradiation. Further irradiation causes plasma generation, NOx formation and lattice oxygen depletion. Partially reduced spinels are represented as MaOb–c. These reactions occur through a chemical looping process in micron-scale domains on the porous catalyst surface. Therefore; it is possible to scale-up this process to obtain NOx from MaOb for nitric acid production and H2 generation from MaOb–c by catalyst re-oxidized by water. Re-oxidation by CO2 delivers CO as fuel. These findings explain the mechanism of conversion of combustion gases (CO2 + N2) to CO and NOx via a chemical looping process. Mechanism of catalyst generation is proposed and the resulting structural inhomogeneity is characterized. Plasma generating catalysts also represent a new form of Radar Absorbing Material (RAM) for stealth and protection from radiation in which electromagnetic energy is dissipated by plasma generation and catalytic reactions. These catalytic RAMs can be expected to be more efficient in frequency independent microwave absorption. [ABSTRACT FROM AUTHOR]

Drinking water denitrification performance of a bench scale membrane bio-reactor (MBR) was investigated as function of hydraulic and biological parameters. The reactor was a stirred tank and operated both in batch and continuous mode. The mixed denitrifying culture used in the batch mode tests was derived from the mixed liquor of a wastewater treatment plant in Erzincan province in Turkey. But the culture used in the continuous mode tests was that obtained from the batch mode tests at the end of the denitrification process. The nitrate contaminated water treated was separated from the mixed liquor suspended solids (MLSS) containing active mixed denitrifying culture and other organic substances by a membrane of 0.2 microm average pore diameter. The results indicated that the use of a membrane module eliminated the need for additional post treatment processes for the removal of MLSS from the product water. Concentration of nitrite and that of MLSS in the membrane effluent was below the detectable limits. Optimum carbon to nitrogen (C/N) ratio was found to be 2.2 in batch mode tests. Depending on the process conditions, it was possible to obtain denitrification capacities based on the reactor effluent and membrane effluent up to 0.18kgm(-3)day(-1) and 2.44 kg m(-2) day2(-1) NO(3-)-N, respectively. The variation of the removal capacity with reactor dilution rate and membrane permeate flux was the same for two different degrees of [MLSS]0/[NO3-N]0 (mass) ratios of 25.15 and 49.33. The present MBR was able to produce a drinking water with NO(3-)-N concentration of less than 4 ppm from a water with NO3-N contamination level of 367 ppm equivalent to a NO(3-)-N load of 0.310 kgm(-3) day(-1). The results showed that MBR system used was able to offer NO(3-)-N removals of up to 98.5%. It was found that the membrane limiting permeate flux increased with increasing MLSS concentration.