高铝碱性废液资源化利用制备活性氧化铝载体

Resource utilization of high aluminum alkaline waste solution to prepare active alumina carrier

  • 摘要: 从废铝基催化剂中回收贵金属时,会产生大量的高铝碱性废液,废液的直接排放不仅会造成铝资源的严重浪费,还可能因其强碱性对环境造成负面影响。目前,关于高铝碱性废液的资源化利用的研究较少,本文对某废铝基催化剂回收过程中产生的高铝碱性废液(Al质量浓度6.594 g/L)进行资源化利用研究。首先,采用碳化法将废液中Al元素转化为拟薄水铝石;然后,将拟薄水铝石样品焙烧制成氧化铝载体。结果表明:通过调整废液中磷的质量分数为2%~3%、溶液苛性比(氧化钠与氧化铝摩尔比)为1.5后,拟薄水铝石的比表面积和胶溶指数显著提高。此外,预成型的拟薄水铝石在温度为450 ℃、恒温3.5 h、升温速率为100 ℃/h条件下焙烧,可获得符合指标的活性氧化铝载体。该工艺可实现高铝碱浸液的资源化利用,且环境友好、无三废产生,具有较好的工业应用前景。

     

    Abstract: The recycling of precious metals from spent aluminum-based catalysts generates a large amount of high-Al alkaline waste solutions, which not only cause a serious waste of aluminum resources, but also may have a negative impact on the environment due to their strong alkalinity. At present, there are few researches on the resource utilization of these high-Al alkaline waste solutions, an investigation into the re-preparation of active alumina carrier from a high-Al alkaline waste solution (Al 6.594 g/L, pH 14) of spent Pd-Al2O3 catalysts by the carbonating-roasting process was performed in this paper. First, the carbonating method was adopted to treat the waste solution, converting the Al therein to pseudo-boehmite; then, the pseudo-boehmite underwent roasting to re-make alumina carrier. Experimental results showed that the P content of 2% ~3% and the caustic ratio (i.e., Na2O to Al2O3 ratio) of 1.5 in the waste solutions are conducive to the significant increase in the specific surface area and dispersion index for the pseudo-boehmite products. In addition, the pseudo-boehmite, after performing, was subjected to roasting under the conditions of temperature 450 ℃, holding time 3.5 h, and heating rate 100 ℃/h, which successfully obtained γ-Al2O3 catalyst carrier that meet the product quality index. This process can achieve the high-efficient resource reuse of high-Al alkaline waste solutions with eco-friendliness and without generation of the three wastes, thus making it promising for industrial application.

     

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