－Catalysts are subject to the conditions in which they must operate．The two most frequent deactivation modes are（1）＿＿sintering 燒結 of the catalytic components and carrier due to high temperature and exposure to（2）＿＿＿poisoning 毒化 from feed contaminants． -催化劑受其必須工作的條件的約束。兩種最常見的失活模式是（1）__sintering 由於高溫和暴露於（2）___poisoning 進料污染物的毒化而使催化成分和載體燒結。
－Automobile catalytic converters where temperature close to 1000^(@)C1000^{\circ} \mathrm{C} are experienced -溫度接近的汽車催化轉化器 （Automobile catalytic converters where temperature close to 1000^(@)C1000^{\circ} \mathrm{C} experience
－Poisoning can occur due to process contaminants - 由於工藝污染物而可能發生中毒 qquad\qquad adsorbing onto or qquad\qquad blocking qquad\qquad 吸附或 qquad\qquad 堵塞
－It is essential to understand the modes of poisoning in order to develop resistant materials – 為了開發抗性材料，瞭解中毒的模式至關重要
5．2 Thermally－induced deactivation 5.2 熱誘導失活
－It is the objective of the catalyst manufacturer to qquad\qquad maximize accessibility of the reactants to the active sites by depositing the catalytic components on a qquad\qquad carrier ． -催化劑製造商的目標是通過將催化組分沉積在 qquad\qquad 載體上， qquad\qquad 最大限度地提高反應物對活性位點的可及性。
－A perfectly dispersed (100%(100 \%qquad\qquad dispersion ）catalyst is one in which every atom（or molecule） of active component is available to the reactants．This is shown as a cartoon in Figure 5.1 where the dots represent the catalytic component（indicated as Pt in the figure）dispersed on a high surface area gamma-Al_(2)O_(3)\gamma-\mathrm{Al}_{2} \mathrm{O}_{3} ． -完全分散的 (100%(100 \%qquad\qquad 分散體）催化劑是指每個原子（或分子）的活性組分都可用於反應物的催化劑，如圖 5.1 中的卡通所示，其中點代表分散在高表面積 gamma-Al_(2)O_(3)\gamma-\mathrm{Al}_{2} \mathrm{O}_{3} 上的催化組分（在圖中表示為 Pt）。
Figure 5．1 Idealized cartoon of perfectly dispersed Pt on a high－surface gamma-Al_(2)O_(3)\gamma-\mathrm{Al}_{2} \mathrm{O}_{3} ． （ :'\because high surface energy） 圖 5.1 完美分散的 Pt 在高表面 gamma-Al_(2)O_(3)\gamma-\mathrm{Al}_{2} \mathrm{O}_{3} 的理想化漫畫。（ :'\because 高表面能）
－Some catalysts are made in this highly active state，but are highly qquad\qquad unstable and -一些催化劑是在這種高活性狀態下製造的，但高度 qquad\qquad 不穩定且 qquad\qquad thermal effects cause crystal growth resulting in a loss of catalytic surface area． Additionally，the carrier with a large internal surface network of pores tends to undergo qquad\qquad 熱效應會導致晶體生長，從而導致催化表面積損失。此外，具有大內表面孔隙網路的載流子往往會經歷 qquad\qquad sintering with a consequent loss in internal surface area． qquad\qquad 燒結后內表面積損失。
－All of these processes are influenced by the nature of the catalytic species，the carrier，and the process gas environment，but mostly by qquad\qquad high temperatures． -所有這些過程都受催化物質的性質、載體和工藝氣體環境的影響，但主要受高溫的影響 qquad\qquad 。
5.2.1 Sintering of the catalytic species 5.2.1 催化物質的燒結
It is common for a highly dispersed catalytic species in the nanosized to undergo growth to structural crystal as a consequence of their high qquad\qquad surface / volume ratio. As this process proceeds, the sites grow larger qquad\qquad decreasing the surface/volume ratio with fewer catalytic atoms or molecules on the qquad\qquad surface of the crystal available to the reactants. In other words, many active sites are buried within the crystal and with fewer sites participating in the reaction, a qquad\qquad decline 埋 in performance is most frequently noted. 由於它們的高 qquad\qquad 表面/體積比，納米級中高度分散的催化物質通常會生長成結構晶體。隨著這個過程的進行，位點變得更大 qquad\qquad ，表面/體積比減小，晶體 qquad\qquad 表面可供反應物使用的催化原子或分子減少。換句話說，許多活性位點埋藏在晶體中，參與反應的位點較少， qquad\qquad 性能下降是最常見的。
This phenomenon/is represented in Figure 5.2. Initially, the sites are well dispersed but undergo qquad\qquad coalescence or crystal growth induced thermally. As catalytic components undergo coalescence, the number of surface sites and the reaction rate qquad\qquad decrease . 這種現象/如圖 5.2 所示。最初，這些位點分散良好，但會發生 qquad\qquad 聚結或熱誘導的晶體生長。隨著催化組分發生聚結，表面位點的數量和反應速率 qquad\qquad 降低。
The driving force for catalytic sintering can be explained by the high 催化燒結的驅動力可以用高來解釋 qquad\qquad surface / volume energy ratio possessed by small crystallites in the nanometer range. Thermodynamically, this is an unstable state and crystal growth, or sintering, occurs to minimized the qquad\qquad 納米範圍內的小晶粒所具有的表面/體積能量比。從熱力學上講，這是一種不穩定的狀態，晶體生長或燒結的發生使
Figure 5.2 Conceptual diagram of sintering of the catalytic component on a carrier. 圖 5.2 載體上催化組分燒結的概念圖。
