Recovery of palladium from palladium phthalocyanine complex adsorbed on silica

This study presents the feasibility of recovering palladium from the spent silica waste wherein palladium is adsorbed on silica as palladium phthalocyanine complexes. The spent silica having palladium phthalocyanine complexes adsorbed on it is thermally calcined in air to partially burn the organic moiety of the complex followed by palladium dissolution as H₂PdCl₄ in hydrochloric acid. The palladium is recovered as PdCl₂ by judiciously adjusting the pH of filtrate obtained. Recovered silica retains its structure and can be re-used.     

钯及钯合金饰品标准样品的研制

遵循国家标准的标准样品工作导则,研制了一套适用于X射线荧光光谱法分析的钯和钯合金饰品标准样品,共5种。按成分的梯度要求,将金属原料混合后熔融,成分合格后铸成厚度为0.18~0.24 mm,直径为16 mm的圆片。利用方差法对均匀性数据进行检查,并委托8家实验室采用不同的实验方法进行定值分析,分析数据用狄克逊检验和夏皮罗-威尔克方法进行检验,结果表明本套标准样品的均匀性良好,定值结果准确。本套标准样品已用于X-射线荧光光谱分析,并被批准为国家标准样品。     

水合肼还原-EDTA滴定法测定氧化钯中钯

氧化钯使用常规的酸溶方法难溶。采用水合肼作为还原剂,于80 ℃时,在氧化钯的悬浮水溶液中,将氧化钯还原为金属钯黑,过滤后,该金属钯黑连同滤纸经过盐酸及硝硫混酸碳化处理后,钯进入溶液,从而解决了难溶氧化钯的溶样难题。然后,于pH 5.8的醋酸-醋酸钠缓冲介质中,以二甲酚橙为指示剂,锌盐返滴定过量EDTA,用丁二酮肟析出与钯等量的EDTA,三氯甲烷萃取丁二酮肟-钯沉淀,锌盐滴定析出的EDTA以测定钯含量,从而建立了水合肼还原-EDTA滴定法测定难溶氧化钯中钯的方法。按照实验方法测定实际样品中钯,结果的相对标准偏差(RSD,n=5)在0.12%～0.20%之间。对基准物质氧化钯中钯进行分析,测定值与理论值相符合。     

液膜萃取法回收废胶体钯活化液中的钯

传统钯回收方法存在成本高、分离效率低,适合高含量钯回收等问题,试验采用液膜萃取法回收废胶体钯活化液中的钯,并考察了内相试剂用量、流动载体用量、表面活性剂用量、油内比、乳水比、外相酸碱度等因素对钯萃取率的影响.结果表明:以9％N503、4％Span80、2％液体石蜡、85％磺化煤油组成膜相,内相试剂EDTA溶液浓度为0....     

The oxidation-reduction kinetics of palladium powder

The cyclic oxidation-reduction of submicrometer sized palladium powder was investigated over the temperature range 848 to 923 K. The total oxygen uptake was found to decrease with increasing number of cycles as a consequence of sintering. Furthermore, sintering was found to be restricted to the reduction steps in these cycles. The relationships for the rate constants of the oxidation and reduction processes are, respectively, K_x, = (1.04)10⁶ exp[-(74.1)10³/RT],k _r = (7.63)10¹² exp[—(207.9)10³/RT]. The activation energies for the oxidation of palladium powder and the reduction of palladium oxide are 74.1 and 207.9 kJ mol⁻¹, respectively.     

Metal-supported palladium membranes for hydrogen separation

The demand for clean and green energy has raised the consumption of hydrogen continuously during the last years. Hydrogen is most economically produced in large scale systems by methane steam reforming followed by pressure swing adsorption (PSA). However, with a rising demand for small-scale production of hydrogen, and as down-scaling to smaller PSA-systems (?<?500?Nm³/h H₂) is not economic, a substantial demand for hydrogen generation using palladium membranes has emerged.

Porous tubes made of an oxide dispersion strengthened powder metallurgy Fe-Cr alloy (trade name ITM) constitute the backbone for the thin solid Pd films. The tubes provide mechanical and chemical long-term stability in atmospheres with hydrogen- and carbon-species at operation temperatures up to 600°C. A porous ceramic diffusion barrier layer (DBL) is deposited between the ITM-backbone and the Pd thin-film to avoid Pd diffusion into the Fe-Cr substrate and thereby ensure long-term integrity of the system. The Pd thin-film with a thickness <?10?μm is applied onto the DBL by a proprietary coating technology.

This paper describes the production route of a tube/diffusion-barrier-layer/Pd-membrane system, its structure and permeation properties.     

低含量钯的分析方法研究

试样经火试金法熔炼和灰吹富集后，贵金属合粒以王水分解，在盐酸介质中，用火焰原子吸收分光光度法测定钯量。该方法的标准样品加入回收率为98．2％～104．1％。