Contrasting Effects of Potassium Addition on M3O4 (M = Co, Fe, and Mn) Oxides during Direct NO Decomposition Catalysis

While the promotional effect of potassium on Co3O4 NO decomposition catalytic performance is established in the literature, it remains unknown if K is also a promoter of NO decomposition over similar simple first-row transition metal spinels like Mn3O4 and Fe3O4. Thus, potassium was impregnated (0.9–3.0 wt.%) on Co3O4, Mn3O4, and Fe3O4 and evaluated for NO decomposition reactivity from 400–650 °C. The activity of Co3O4 was strongly dependent on the amount of potassium present, with a maximum of ~0.18 [(µmol NO to N2) g−1 s−1] at 0.9 wt.% K. Without potassium, Fe3O4 exhibited deactivation with time-on-stream due to a non-catalytic chemical reaction with NO forming α-Fe2O3 (hematite), which is inactive for NO decomposition. Potassium addition led to some stabilization of Fe3O4, however, γ-Fe2O3 (maghemite) and a potassium–iron mixed oxide were also formed, and catalytic activity was only observed at 650 °C and was ~50× lower than 0.9 wt.% K on Co3O4. The addition of K to Mn3O4 led to formation of potassium–manganese mixed oxide phases, which became more prevalent after reaction and were nearly inactive for NO decomposition. Characterization of fresh and spent catalysts by scanning electron microscopy and energy dispersive X-ray analysis (SEM/EDX), in situ NO adsorption Fourier transform infrared spectroscopy, temperature programmed desorption techniques, X-ray powder diffraction (XRD), Raman spectroscopy, and X-ray photoelectron spectroscopy (XPS) revealed the unique potassium promotion of Co3O4 for NO decomposition arises not only from modification of the interaction of the catalyst surface with NOx (increased potassium-nitrite formation), but also from an improved ability to desorb oxygen as product O2 while maintaining the integrity and purity of the spinel phase.

Evaluation of the changes in the Radiocaesium Interception Potential (RIP) of Japanese and European soils based on their potassium content, mineralogy and agricultural zeolite amendments

<p>After the Fukushima Daiichi Nuclear Power Plant (FDNPP) aftermath in 2011, potassium addition has been increasingly valued as the most effective countermeasure for soil remediation of polluted sites. Potassium is a competing cation with caesium during plant root uptake. Recent studies have elucidated that potassium application can increase the Radiocaesium Interception Potential (RIP), a key parameter that determines the radiocaesium selectivity in soil and therefore its phytoavailability. The RIP is determined as the product of the distribution coefficient of caesium and the concentration of potassium in soil solution, considering the occupation in exchange regular sites but especially in the so-called frayed-edged of the 2:1 phyllosilicate layers of clay minerals, that account for most of the high-selectivity sites for caesium. In order to increase soil RIP, mineral amendments -especially zeolite- were applied in Japanese target fields as a major measure for safe agricultural production. In this study, we aimed at the determination of the RIP of Japanese and European soils with different clay mineralogy, as a key parameter for the solid-liquid distribution of radiocaesium in soils. To do so, we analysed the clay mineralogy of soils by X-Ray diffraction (XRD), as well as the solid and soil solution phases of five types of soils with different potassium fixing capacity by atomic absorption spectrometry (AAS) and ionic chromatography (IC), respectively. As potassium fixation varies among soils, we expected very different relationships between their potassium content and RIP. Their RIP was determined by spiking with 1-2 KBq of radiocaesium-134 prior to the use of thallium doped sodium iodine scintillator (NaI(Tl)). Both solid phase exchangeable caesium and soil solution caesium were analysed by inductively coupled plasma mass spectrometry (ICP-MS). Partial findings for Japanese soils showed a potassium fixing rate of approximately 93% for vermiculitic soils, while for imogolitic Andosols with low 2:1 phyllosilicate clay mineral content, only 17% of potassium addition was determined to be fixed. The fixation capacity for smectitic soils reached 57%. Furthermore, additional research is currently being done regarding RIP determination of several agricultural soils and with and without zeolite amendments. The final results will be shown in the EGU General Assembly 2020.</p>

The Effect of Potassium on Cobalt-Based Fischer–Tropsch Catalysts with Different Cobalt Particle Sizes

The effect of K on 20%Co/0.5%Re/γ-Al2O3 Fischer–Tropsch catalysts with two different cobalt particle sizes (small, in the range 6–7 nm and medium size, in the range 12–13 nm) was investigated. The catalyst with the smaller cobalt particle size had a lower catalytic activity and C5+ selectivity while selectivities towards CH4 and CO2 were slightly higher than over the catalyst with larger particles. These effects are ascribed to lower hydrogen concentration on the surface as well as the lower reducibility of smaller cobalt particles. Upon potassium addition all samples showed decreased catalytic activity, reported as Site Time Yield (STY), increased C5+ and CO2 selectivities, and a decrease in CH4 selectivity. There was no difference in the effect of potassium between the sample with small cobalt particles compared to the sample with medium size particles). In both cases the specific activity (STY) fell and the C5+ selectivity increased in a similar fashion.

EFFECT OF TIMINOR AND RATES OF POTASSIUM ON BREAD WHEAT QUALITY AND SOME OTHER CHARACTERES

A field experiment was conducted at the experimental farm, Dept. of Field Crop, Coll. of Agriculture, Univ. of Baghdad ,during 2011-2012, to study the effect of potassium fertilizer levels and appilication stage on bread wheat grains quality Triticum asetivum L.(Var- Abu-Ghraib-3) and some other characteres . Factorial experiment was conducted in RCBD design with three replication involved two levels of potassium 120,180 kg.ha-1 and control treatment the second factor was three stage of application (tillering ,Booting , flowering). The results shows non significant differ between potassium leveles for all studied traits, except havest index.The potassium level 180 kg.ha-1 produced plants with highest harvest index (38.17%), in comparison to the level 120 kg.ha-1, (36.82%).The application stage at flowering time produced grains with higher protein (12.18%), when compard to the tillering and booting stages (11.32% and 12.17%) respectively. The potassium application stage at tillering was superior in protein yield and harvest index 0.935 mg.ha-1 and 40.37%, respectively. It can be conclude that potassium addition stage was more important than, it,s dosages.