Gas-phase selective oxidation of toluene on TiO2–sepiolite supported vanadium oxides: Influence of vanadium loading on conversion and product selectivities

Gas-phase selective oxidation of toluene has been carried out on vanadium oxide systems (5–20 wt.% of V₂O₅, equivalent to 0.4–1.7 theoretical monolayers) supported on TiO₂–sepiolite (with titania loading around the theoretical monolayer, 12 wt.%) and on sepiolite. A study has been made on both the influence of vanadia loading and of the support on the catalytic behaviour of the supported vanadium systems. The reducibility by H₂ TPR was also studied as well as the acid and basic/redox sites from the results of conversion of the 2-propanol test reaction of the solids. Benzaldehyde, benzoic acid and several coupling products were the main ones detected, attaining over 50% selectivity towards the benzaldehyde and benzoic acid products at a total conversion around 10%. The activity and selectivity to the selective products exhibited by vanadium systems supported on mixed support were superior to those exhibited by the systems supported on sepiolite and increased notably in both series with the increase in vanadium loading. The best catalytic behaviour exhibited by the vanadium systems supported on mixed support, which also exhibited the highest density of sites capable of being reduced (as well as their reducibility) and of those responsible for propanone formation, could be attributed not only to the different balance of the vanadia species existing in the two supports (monomeric + oligomeric/polymeric), but also to such other factors as the nature of the support and, concretely, its chemical composition.     

测辐射热计的微桥研制和Vox膜成膜研究

介绍了测辐射热汁的工作原理、器件结构的几何形状和研制状况,叙述了测辐射热计材料的特性及制备技术.     

云南锰矿选矿现状与前景分析

云南锰矿资源丰富,具有品位高、低磷低铁、易选等特点。文章概述了斗南、鹤庆、建水等锰矿的选矿科研进展情况,三个锰矿均可采用强磁选或磁-重选流程选别,可提高品位8—12％;精矿含锰可达33—35％,锰回收率在80％以上的好结果。     

全面留矿法采场顶板支护和落矿爆破工艺的研究

本文介绍的接杆锚杆护顶技术和上向眼大孔距多排微差爆破落矿技术，解决了逐昌金矿全面留矿法采矿工艺中存在的采场顶盘围在面积冒落和采场落矿爆破效果差、效率低这两个问题。     

应用硫酸铵提高乌拉嗄金矿石浮选回收率试验研究

经试验发现应用一种化学肥料硫酸铵可以显著提高乌拉嘎金矿石的浮选回收率。闭路试验尾矿工艺矿物学鉴定证明，以硫酸铵作为调整剂的浮选过程中，微细粒单体金和金与石英边生体被有效回收。     

优化锰铁高炉配矿结构

介绍了通过优化高炉锰铁烧结矿原料结构，改善了烧结矿性能，使锰铁冶炼取得了增产、节焦、降成本的明显效果。     

广西天等贫氧化锰矿石的选矿试验研究

天等锰矿石属高硅、低磷贫氧化锰矿石，矿物结晶粒度微细。选矿试验中进行了洗矿、强磁和重选流程研究，试验结果表明，洗矿效果较好，当原矿含锰１６．８５％，经一段洗矿后，可获得含锰２９．７７％，锰回收率为８６．２７％的锰净矿。     

Investigation of the Effects of some Parameters in the Production of Chromate from Chromite Ores in Iskenderun Region

The conversion of chromite ore from iskenderun region into chromate was investigated. Firstly, the chromite ore was analysed using conventional chemical methods. Then, the effect of some parameters such as roasting time, temperature and the amount of additives on the conversion efficiency to the chromate was examined. The optimum roasting conditions were determined as 300°C, 2 hours, 10 times the stoichiometrically required amounts of NaClO₃ and 6 times the stoichiometrically required amounts of KOH. Under these conditions, the maximum recovery of chromate was found to be 100%. The product obtained from the roasting process was leached with water to produce a clean chromate solution. The effect of temperature and solid/liquid (S/L) ratio was investigated in the water leaching experiments. The optimum experimental results obtained were 100% at a 1:5 solid to water ratio at 25°C and 20 min leaching period. The chromate solution was purified using conventional purification processes.     

房柱法在斗南锰矿缓倾斜极薄矿体的试采

本文介绍了房柱法在斗南锰矿缓倾斜极薄矿体(厚度小于1.2m)中的试验情况。经试采证明,该方法是回采缓倾斜极薄矿体的一种有效方法。采场生产能力可达48t/d,矿房回采率为87.1％,矿块回采率为80.4％,废石混入率为9.3％。采用了预裂爆破、松动爆破和抛掷爆破技术,对减少粉矿以及矿石的贫化和损失,起到了很好的作用。     

三叶状钒催化剂的研制

介绍了三叶状钒催化剂的研制。工业宏观活性评价和通气测试表明，三叶状催化剂性能优良，其床层压力降介于圆柱状和环状催化剂之间，为圆柱状催化剂的70％左右。在相同的转化条件下，相对于环状催化剂，三叶状催化剂的装填量可减少16．7％。