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61.
The selective oxidation of n-butane to maleic anhydride(MA) on a vanadium-phosphorus oxide (VPO) catalyst was studied using on-line gas-chromatography combined with mass spectrometry(GC-MS) and transient response technique.The reaction intermediates,butene and furan,were found in the reaction effuent under near industrial feed condition (3% butane 15% O2),while dihydrofuran was detected at high butane concentration (12% butane,5%O2).Some intermediates of MA decomposition were also identified.Detection of these intermediates shows that the vanadium phosphorus oxides are able to dehydrogenate butane to butene,and butene further to form MA.Based on these observations,a modified scheme of reaction network is proposed.The transient experiments show that butane in the gas phase may directly react with oxygen both on the surface and from the metal oxide lattice,without a proceeding adsorption step.Gas phase oxygen can be adsorbed and transformed to surface lattice oxygen but it can not participate in selective oxidation.Adsorbed oxygen leads to deep oxidation,while lattice oxygen leads to selective oxidation. 相似文献
62.
Phosphorus modification of ZSM-5 leads to extra framework P5+ and probably incorporation of +3 valence state of P in the framework. The resulting system has increased Brønsted acidity. Theoretical calculations also favour the postulate that phosphorus in +3 valence state can be incorporated into the lattice. 相似文献
63.
净化黄磷尾气合成甲酸甲酯研究 总被引:4,自引:0,他引:4
用净化黄磷尾气为原料与甲醇液相合成甲酸甲酯 ,并对影响一氧化碳及甲醇转化率、甲酸甲酯时空收率等的因素进行了研究。研究结果表明 ,随着主催化剂浓度或反应压力的增大 ,一氧化碳转化率及甲醇转化率均提高 ;助剂的加入可以大大提高甲酸甲酯时空收率和延长催化剂的寿命。优化的反应条件为 :主催化剂 (甲醇钠 )浓度 0 .4mol L ;助催化剂吡啶浓度 1.74mol L ;温度 80℃ ;时间 160min ;压力 4MPa。在此条件下 ,黄磷尾气中一氧化碳及甲醇转化率可分别达到 95 .5 %和 43%。 相似文献
64.
M. Oyanarte G. Besga M. Rodríguez M. Domingo A. G. Sinclair 《Nutrient Cycling in Agroecosystems》1996,47(3):261-269
Dairy farming is the main agricultural activity of the Basque Country. A dairy farm is characterized as a system with soils and crops, forage, cattle and manure as main components, and in such a system, nutrient cycling is very important to maintain soil fertility and optimize forage production. To quantify nutrient transfers in the cycle, a simple system was developed and has been applied to seventeen farms to examine its ability to achieve a balanced P and K fertilization. These farms have provided data on inputs (fertilizer, feeds, concentrates), pasture and manure management, and outputs (milk production), and soil samples have been taken from farm pastures. Phosphorus and K in excreta and uneaten pasture is used with a relatively high efficiency as suggested by the relatively high efficiency of P and K utilization by the pasture that usually ranges from 70 to 90%. Concentrate feeding (3000 kg cow–1 yr–1) represents one of the main P and K inputs in Basque Country dairy farms, averaging 26 and 66 kg ha–1, respectively. Besides, release of K in the soil through slow liberation from non-exchangeable sites was estimated as 30 kg ha–1. Thus, a high efficiency in excreta recycling would diminish substantially P and K mineral fertilizer needs. Farm nutrient budgets appear to be a convenient tool for determining nutrient shortages and surpluses at farm level, and thus they are considered as a first step to support a better management of maintenance fertilization of permanent pastures. 相似文献
65.
Mussoorrie rock phosphate (MRP), MRP + pyrite (25% by weight), diammonium phosphate (DAP), ammonium polyphosphate (APP) and nitrophosphate (NP) were compared in a field experiment as fertilizers for wheat. At 20 kg P ha–1, MRP was only 6 per cent as effective as DAP. However, when it was mixed with pyrite, the efficiency of MRP increased to 64 per cent at 20 kg P ha–1 compared with 97 per cent at 40 kg P ha–1. The P requirement for a targeted yield for 4.5 t ha–1 decreased from 39.4 kg P ha–1 as MRP to 23.7 kg P ha–1 as MRP + pyrite. Of the other P fertilizers studied, NP was as effective as DAP, whereas APP was 9 to 37 per cent more effective than DAP. However, the P requirement as DAP, NP and APP for a targeted yield of 4.5 t ha–1 was similar (11 ± 0.5 kg P ha–1). 相似文献
66.
67.
68.
K Harmsen 《Nutrient Cycling in Agroecosystems》1984,5(4):371-382
Agronomic efficiency (AE) is defined as the increase in economic yield of a crop per unit fertilizer applied. Components of AE are physiological efficiency and apparent recovery fraction. The latter can be further separated into uptake efficiency and availability index. Ways to increase the nitrogen fertilizer use efficiency in rainfed agriculture through fertilizer management are discussed. 相似文献
69.
有机磷化物制备羟基磷灰石工艺条件的探讨 总被引:1,自引:0,他引:1
探索用有机磷化物制备羟基磷灰石的工艺条件:采用硝酸钙、氨水、磷酸三丁酯为原料进行正交对比研究,优化得到了制备较佳羟基磷灰石的工艺条件。优化的工艺条件为:原料中Ca/P(molar ratio)1.67;Ca(NO3)2、4H2O/NH3H2O(g/g)为0.99;烧结温度为850℃:恒温时间为5h,并对合成的样品进行了化学和红外光谱的分析。 相似文献
70.
高产小麦磷钾效应和适宜氮磷钾配比研究 总被引:2,自引:0,他引:2
黄泛冲积石灰性土壤在适宜施氮水平下磷钾不同用量及配比对小麦生长的影响表现为:(1)磷肥以中量施用水平(每公顷施用P2O5120kg)增产效果最好,分别比未施磷、低量施用水平(每公顷用P2O548kg)增产30.82%、20.27%,高量施用水平(每公顷施用P2O5192kg),虽然比中量施用水平表现出增产,但增产幅度很小,只有2.85%;(2)钾肥对小麦的增产效应小于磷肥,只有在施用磷肥的基础上配施钾肥,才能使钾的效应得到充分发挥;(3)小麦全生育期氮磷钾施用比例1∶0.5∶0.5为最佳,每公顷施用N240kg、P2O5120kg、K2O120kg效益最高。 相似文献